Recreating a Python Simulation in Scratch

Cooriemungle_Water_Tank_Cow_Monster-wikimedia-commonsIn my last post, I added my own modifications to the tutorial  Making Breakout by Leonel at codeNtronix.   He also has a number of tutorials about drawing 3D graphics using python and pygame.  I was intrigued by his simulation of a 3D Starfield made using Python and Pygame.  (Thanks Leonel for creating such useful tutorials).


His simulation uses a few basic 3D to 2D algorithms, which I don’t fully understand but they are effective at creating the desired effect.  He created this effect with just 80 lines of source code,  Click here to download the full source code from CodeNTronics.

I analysed the code myself to see if I could recreate this simulation in Scratch.

3D Starfield

Scratch Code:  Takes 31 lines of code and painted backdrop and sprite costume in the paint editor.starfield-scratch-stage-codestarfield-scratch-starsprite-code


Python code:  81 lines from CodeNTronics, with comments added by me.

# """
# 3D Starfield Simulation
# Developed by Leonel Machava <>
# """
import pygame, math
from random import randrange

class Simulation:
    def __init__(self, num_stars, max_depth):  # SM- each star needs an individual variable for x,y,depth.  
        pygame.init()   # SM-- does a bunch of pygame stuff to set up screen and clock.

        self.screen = pygame.display.set_mode((640, 480))
        pygame.display.set_caption("3D Starfield Simulation (visit")

        self.clock = pygame.time.Clock()
        self.num_stars = num_stars
        self.max_depth = max_depth

        self.init_stars()  # SM- Tells the program to make the list of stars

    def init_stars(self):
        """ Create the starfield """
        self.stars = []
        for i in range(self.num_stars):
            # A star is represented as a list with this format: [X,Y,Z]
            star = [randrange(-25,25), randrange(-25,25), randrange(1, self.max_depth)]

    def move_and_draw_stars(self):
       # """ Move and draw the stars   """   SM Converts the xy coordinates to cartesian to centre stars on screen
        origin_x = self.screen.get_width() / 2
        origin_y = self.screen.get_height() / 2

        for star in self.stars:
            # The Z component is decreased on each frame. SM-- Star Moves closer
            star[2] -= 0.19

            # If the star has past the screen (I mean Z<=0) then we
            # reposition it far away from the screen (Z=max_depth)
            # with random X and Y coordinates.
            if star[2] <= 0:
                star[0] = randrange(-25,25)
                star[1] = randrange(-25,25)
                star[2] = self.max_depth

            # Convert the 3D coordinates to 2D using perspective projection.
            k = 128.0 / star[2]   # SM I don't know where Leonel got this constant 128/depth but it works
            x = int(star[0] * k + origin_x)  #SM-- moves starfield origin towards centre of screen
            y = int(star[1] * k + origin_y)

            # Draw the star (if it is visible in the screen).
            # We calculate the size such that distant stars are smaller than
            # closer stars. Similarly, we make sure that distant stars are
            # darker than closer stars. This is done using Linear Interpolation.
            if 0 <= x < self.screen.get_width() and 0 <= y < self.screen.get_height():
                size = (1 - float(star[2]) / self.max_depth) * 5
                shade = (1 - float(star[2]) / self.max_depth) * 255

    def run(self):
        """ Main Loop """
        while 1:
            # Lock the framerate at 50 FPS.

            # Handle events.
            for event in pygame.event.get():
                if event.type == pygame.QUIT:


if __name__ == "__main__":
    Simulation(256, 32).run()


The python program presents a much more realistic starfield and is much more versatile. But the scratch program accomplishes the same task in 1/4 the length and it is much easier for me to tinker with the variables and formulas to change the appearance in SCRATCH. It is an accomplishment that I can understand enough of Python to recreate the essential features of a program in SCRATCH. To use the analogy of spoken languages, I think that I have progressed to the point that I can understand a bit of what I read and hear in PYTHONESE, but I cannot yet speak it like a native. This is very good progress for 10 days. To extend the spoken language analogy, one of the common exercises for people learning a second language is to translate passages from one language to another.  That is exactly what I attempted here, and I am quite satisfied with the results.

In which I Pursue Progress with Programming in Python

99er MagazineIn  1981 or so, my brother and I were 12 and 13 years old and we both had paper routes.  We pooled the fruits of our paper carrier jobs, and Dad took us down to the Alberta Treasury Branch where he co-signed a $1200 personal loan at a whopping 23% interest so that we could buy our first personal computer– a TI-99/4.  In fact it was the first personal computer anyone had in our neighbourhood.  We poured over the accompanying manuals, got all sorts of books from the library, and subscribed to 99er magazine.  These early computer enthusiast magazines offered articles about the future of computing, ads for enticing new peripherals and gadgets, and most importantly programs.  Each magazine contained printouts– recipes I guess, for dozens of programs.  We learned to program by painstakingly copying programs from printouts in these magazines, even more painstakingly debugging our errors then figuring out how to fix the inevitable mistakes in the magazine’s code.

30 year later, as I make the transition from SCRATCH, to PYTHON, I find myself transported back to the same learning process.  As I undertook to learn a new programming language, I found myself seeking out familiar “Teach yourself programming by copying these game’ books.  But this time I did not need to go to the magazine stand, or the library, or order in by mail.  The resources are all a google away.  I think it says something about my personal learning style that I chose the cookbook style of print resources over the many multimedia and video tutorials available on youtube.

I’ve spent most of the last week trying to understand some of the basic structure and commands of python, as I worked my way through a variety of tutorial programs.  First impression is compared to scratch there is alot more fiddly typing and figuring out exactly how to initialize then execute each step.  Unlike scratch, it is much harder in python to just poke around and see what will happen.  If you don`t know the precise order, structure, and syntax for any small part… the whole program may not even start.  I think here is a fundamental difference between Scratch and python.  Constructivist philosophy is at the core SCRATCH.  It is designed to be explored, tinkered with and discovered.  On the other hand, Python is designed to be functional, readable, and infinitely extensible.  Alex Martelli, author of the Python Cookbook, summed up the Python Philosophy:

To describe something as clever is not considered a compliment in the Python culture.” Python’s philosophy rejects the Perl “there is more than one way to do it” approach to language design in favor of “there should be one—and preferably only one—obvious way to do it”.  From:  Python Programming Language on Wikipedia.

Bricka by codeNtronix

Download the original Brika Source code from codeNtronix

and here is my revised source code for Bricka.

 bricka (a breakout clone)
 Developed by Leonel Machava <>

with revisions by Sean McGaughey
during Creative Computing Online Workshop

import sys, pygame
from pygame.locals import *

SCREEN_SIZE   = 640,480

# Object dimensions
BALL_RADIUS   = int(BALL_DIAMETER / 2)   #source code was just BALL_DIAMETER / 2 This through an error of floating point vs Int error
                                        # I added an int function to make sure it is an integer value


# Paddle Y coordinate

# Color constants
BLACK = (0,0,0)
WHITE = (255,255,255)
BLUE  = (0,0,255)
BRICK_COLOR = (200,200,0)

# State constants

mousex = 0 #x coordinate of mouse event
mousey = 0 # y coordinate of mouse event

class Bricka:

    def __init__(self):

        self.screen = pygame.display.set_mode(SCREEN_SIZE)
        pygame.display.set_caption('bricka (a breakout clone by')

        self.clock = pygame.time.Clock()

        if pygame.font:
            self.font = pygame.font.Font('freesansbold.ttf',20)
            self.font = None


    def init_game(self):
        self.lives = 3
        self.score = 0
        self.state = STATE_BALL_IN_PADDLE

        self.paddle   = pygame.Rect(300,PADDLE_Y,PADDLE_WIDTH,PADDLE_HEIGHT)
        self.ball     = pygame.Rect(300,PADDLE_Y - BALL_DIAMETER,BALL_DIAMETER,BALL_DIAMETER)

        self.ball_vel = [5,-5]


    def create_bricks(self):
        y_ofs = 35
        self.bricks = []
        for i in range(7):
            x_ofs = 35
            for j in range(8):
                x_ofs += BRICK_WIDTH + 10
            y_ofs += BRICK_HEIGHT + 5

    def draw_bricks(self):
        for brick in self.bricks:
            pygame.draw.rect(self.screen, BRICK_COLOR, brick)

    def check_input(self):
        for event in pygame.event.get(): # event handling loop
            if event.type == QUIT or (event.type == KEYUP and event.key == K_ESCAPE):
            elif event.type == MOUSEMOTION: # I added these mouse controls.  It works well.
                mousex, mousey = event.pos
                if mousex >= MAX_PADDLE_X:
                    self.paddle.left = MAX_PADDLE_X
                    self.paddle.left = mousex

            elif event.type == MOUSEBUTTONUP:
                mousex, mousey = event.pos
                self.paddle.left = mousex
                mouseClicked = True
                if self.state == STATE_BALL_IN_PADDLE:
                    self.state = STATE_PLAYING

        keys = pygame.key.get_pressed()

        if keys[pygame.K_LEFT]:
            self.paddle.left -= 5
        if self.paddle.left < 0:             self.paddle.left = 0         if keys[pygame.K_RIGHT]:             self.paddle.left += 5         if self.paddle.left > MAX_PADDLE_X:
            self.paddle.left = MAX_PADDLE_X

        if keys[pygame.K_SPACE] and self.state == STATE_BALL_IN_PADDLE:
             self.state = STATE_PLAYING
        elif keys[pygame.K_RETURN] and (self.state == STATE_GAME_OVER or self.state == STATE_WON):


    def move_ball(self):
        self.ball.left += self.ball_vel[0]  += self.ball_vel[1]

        if self.ball.left <= 0:             self.ball.left = 0             self.ball_vel[0] = -self.ball_vel[0]         elif self.ball.left >= MAX_BALL_X:
            self.ball.left = MAX_BALL_X
            self.ball_vel[0] = -self.ball_vel[0]

        if < 0:    = 0             self.ball_vel[1] = -self.ball_vel[1]         elif >= MAX_BALL_Y:
            self.ball_vel[1] = -self.ball_vel[1]

    def handle_collisions(self):
        for brick in self.bricks:
            if self.ball.colliderect(brick):
                self.score += 3
                self.ball_vel[1] = -self.ball_vel[1]

        if len(self.bricks) == 0:
            self.state = STATE_WON

        if self.ball.colliderect(self.paddle):
            self.ball_vel[1] = -self.ball_vel[1]
        elif >
            self.lives -= 1
            if self.lives > 0:
                self.state = STATE_BALL_IN_PADDLE
                self.state = STATE_GAME_OVER

    def show_stats(self):
        if self.font:
            font_surface = self.font.render('SCORE: ' + str(self.score) + ' LIVES: ' + str(self.lives), False, WHITE)
            self.screen.blit(font_surface, (205,5))

    def show_message(self,message):
        if self.font:
            size = self.font.size(message)
            font_surface = self.font.render(message,False, WHITE)
            x = (SCREEN_SIZE[0] - size[0]) / 2
            y = (SCREEN_SIZE[1] - size[1]) / 2
            self.screen.blit(font_surface, (x,y))

    def run(self):
        while 1:
            for event in pygame.event.get():     # I added these lines from Sweigart, making Games with Python
                if event.type == pygame.QUIT:
                    sys.exit                    # To check for Quit


            if self.state == STATE_PLAYING:
            elif self.state == STATE_BALL_IN_PADDLE:
                self.ball.left = self.paddle.left + self.paddle.width / 2
        = - self.ball.height
                self.show_message('PRESS SPACE TO LAUNCH THE BALL')
            elif self.state == STATE_GAME_OVER:
                self.show_message('GAME OVER. PRESS ENTER TO PLAY AGAIN')
            elif self.state == STATE_WON:
                self.show_message('YOU WON! PRESS ENTER TO PLAY AGAIN')


            # Draw paddle
            pygame.draw.rect(self.screen, BLUE, self.paddle)

            # Draw ball

  , WHITE, (self.ball.left + BALL_RADIUS, + BALL_RADIUS), BALL_RADIUS)

            self.show_stats ()

if __name__ == '__main__':



Here is my first attempt at programming a game in Scratch from November of 2011.


CCOW – Week 4 Wrapup Post and Python Project Progress

CC photo by on flickrIt’s the end of the last  (Professional activity) day of school.  The children finished, and my office/classroom is packed up till late August.

Back to my regularly scheduled CCOW Activities.

I dabbled this week at some of the Week 4 activities.  I skipped the advanced features activity because I have been trying to use some of Scratch 2.0s advanced features in previous weeks.  I looked at some of the resources on the ScratchEd site for the Activity Exploration but I did not keep track of the ones I looked at.

My focus has been on my Personal Project to Pursue Programming in Python as a Pastime.    As I delve into the resources, my  focus is getting clearer.

1) I want to build upon my experience using Scratch to teach myself how to Code in Python.

2) I want to document my personal experience and explore how I can help my students make the transition from SCRATCH to real-world programming.

The focus for me is strongly on 1)– I (Sean McGaughey- life long learner, and dabbler in all sorts of creative endeavours) want to learn more advanced programming.  I was thinking that because of this primary focus that my project might be beyond the scope of the CCOW workshop.   I think I was mistaken.  All the feedback I have had about this project has been positive.  I was greatly encouraged when 2 of the facilitators (Ingrid and Laura I think) each mentioned my project on CCOW office hours yesterday.   It seems that many people are interested in how to move from SCRATCH’s controlled sandbox into the big Programming Playground beyond.  I hope as I chronicle my transition it can be helpful for other teachers and their students.

Reflections from my first few days working with python.

  • I chose python over javascript, java, or other multipurpose languages because it seemed to be used for tons of things from games to the internet to sciencific calculations, to mobile apps.  Also there are tons of free online resources and tutorials to teach yourself python, and many of them are geared towards children.  I am keeping a list of the links I find using diigo.
  • I spent a lot of time researching IDE (Integrated Development Environments) for python.  Think– word processors that also check your code for you, help you by automagically finishing what you are typing, and like scratch provide some kind of stage or window to show your code in action.  Python comes with a perfectly good IDE called IDLE, but I investigated about 6 before I settled upon pyscripter for windows.  It autosuggests commands and variables,  it automatically completing brackets and auto-indents lines of code into blocks.  This makes it easier for me to learn the correct use of spaces and indentation.  It also has very intuitive syntax-checkers and debuggers which are also helping me understand how to structure code in python.  *Next week I should write a blog post comparing the IDE of scratch to some of those available for python and other programming languages.
  • Does anyone know of an IDE for python that has the same main features as SCRATCH– ie Stage to run the program, heirarchical lists or menus of available commands, editor to put the code in?
  • Bah!  The Training Wheels are definitely off.  Python is fiddly– Spaces, punctuation, case, and indentation all have meaning.  Make a simple error in any of them and the program will not run.   (Fortunately a good IDE will help to make it easier to learn the ‘rules of the road’ for how code should be structured.

Resources I have used this week:

I have been trying to specifically use ‘python for kids’ books because they are aimed at beginners and because I want to know what is available for my students.  I found 3 to be very useful.

All three of these resources are available for free online, but each of the authors also has newer revised editions of these books available for purchase as paper books or ebooks.   I like the playful, humour filled style of all three authors and I am sure kids would enjoy them too.

Potential blog posts:  

      • Compare the object oriented nature of scratch (Sprites and Code blocks snapped together) with python (Functions, modules and libraries).
      • Prepare some code examples in both Scratch and Python
      • Make a bit of a graphical metaphor using buckets, boxes or something to show how python interchangeably uses variables, lists, tuples, functions, libraries etc… *Basically– anything you can give a name and value to can be used in place of any other thing that outputs a value– “If you know the correct syntax– erm ‘the magic words’ “.

That’s all for this week.  I’m looking forward to spending more time with CCOW now that school is over.

 My other week 4 posts: 

Coder’s Log Terradate 26.06.2013

Week 4- Workshop Project: Defining and Planning


Coder’s Log Terradate 26.06.2013

pythonI got some great feedback about my post this morning that for my CCOW project what I wanted to do is leave the SCRATCH sandbox and learn to code in Python.

Eric Schilling responded on Google Plus:

Have you checked out Blockly from Google? It’s a web-based, graphical programming editor, similar to Scratch except it will provide the code in a number of different programing languages (phyton, xml, etc.)., I found Code Academy was a wonderful resource to learn new programming languages.

I checked out both resources and they are quite useful.  Blocky seems to be a little more clunky than scratch, and it is also a sandbox type learning environment.  But it may be very useful transition for figuring out how things work in python by snapping somewhat familiar blocks together and viewing the python code that it outputs.
The codeacademy resource looks good, but I went looking for some other free kid friendly “How to code in python books” so that I could recommend some resources for children ready to make the move from Scratch.
Here on the blog, Claude commented:
Your blog is always very interesting Sean! Ok, now I have maybe too straightforward question for you : why don’t you set your objective to simply learn python and make a game with it? I know the course is supposed to be based on scratch, but it sounds like you’re twisting your multiple objectives to fit the course. And I think that when you teach with scratch, at some point you want introduce student too “fuller” languages, and I hear python is the natural second step. So it would be very coherent to prepare like the next step learning Python, wouldn’t it?
Thank you Claude.  You helped clarify to me about my project.  Rather than try to convert python code to scratch or vice versa, I will just document my own transition from the closed sandbox of scratch to the larger playground afforded by python.
So tonight I explored a number of beginner Python resources including:
Al Sweigart has 3 comprehensive free books geared at teaching nonprogrammers and children how to program python through games.

I settled on using the Python Book for Beginners by Jody S. Ginther  because it offers  a very simple short (58 page) primer to downloading and beginning to program with Python.    The first thing I did after I downloaded the book, is followed its instructions to Download Python for Windows and install it.  Don’t worry if you use Mac or Linux, there are flavours of Python for most operating systems.

Then I just started working through the book and following the code examples to make my first programs.  My first impressions of python are that through my use of Scratch and programming in BASIC 30 years ago, I know the basic principals of programming.  I will just have to start to learn the commands, syntax and peculiarities of python.  I like how the IDLE python editor uses color commands to differentiate between different types of commands.  It also automatically indents certain commands to make it easy to see which commands belong with which blocks of code.

My other first impression is that I realize now that the training wheels are definitely off.  Scratch offers a kind of mixed sandbox with it’s integrated graphics and audio editors, background support and focus on making multimedia programs easily.  There is a ton of programming and arranging you can do in scratch without ever snapping together a code block  (Ie setting up a picture or scene with a variety of text, paintings, and sprites).     Not so in python (or other object oriented languages).  If you don’t explicitly tell the computer to do something in the code– it will not happen.

Last thought before bedtime.  Today’s refined project objective for my CCOW project:  Document my transition from using Scratch to learning python on this blog.   Try to keep in my mind tips and resources that would help students make this transition.

Week 4- Workshop Project: Defining and Planning

cube of RubikHere it is.  We are midweek through the crazybusy last week of school, so I have not been able to do much with CCOW except for watching the office hours while packing up my little office/classroom for the summer.

I have been dreading the project part of the workshop because I had too many ideas and many of them were larger than I think I could tackle in 3 weeks.  One of them is worth mentioning just to get a link in here.  There is a good start to an Introduction to Scratch handbook on Wikibooks that is incomplete.  I considered seeing if a group of people would be interested in joining wikibooks to work on completing this scratch book.   It could turn into a project which is waaay larger than the scope of this workshop. It would involve collaborating with another online community and learning it’s culture and way of doing things.  And I think, to a certain degree it would be re-inventing the wheel because the Scratch wiki  contains all the information such a book would have and more, and it is actively maintained.  Also during my too brief explorations of the Resources section of ScratchED, I think that there are plenty of other easily accessible Scratch primers and activities, so this one is not needed.

That got me thinking about Objectives, aka learning goals, aka purpose, aka What are we supposed to do, aka what do I what to do.  My objectives and goals for participating in this online workshop are individual, as are those of each of the other participants in the workshop.  And the facilitators each of reasons (objectives) for participating in CCOW.  Not only that, but each person in the process may have multiple (sometimes conflicting) goals.   For instance, I know that the lead facilitator of CCOW, Karen Brennan, stated that she wanted to try to organize a MOOC using a new google platform that allows one to design and host online courses.  That sounds like a fine personal professional learning goal for her, and we all are benefitting from the fruits of her work on that goal.

But what are my learning goals for participating in this workshop?  I had to reflect on that a bit because in my teaching I often start doing the planning and teaching before I fully realize my objectives.  (I think this is a reality in any kind of teaching and learning environment).

  • I signed up because I have been teaching Scratch to elementary students  (and to other teachers) for about 3 years but I always feel that I never have the time to play with it myself– to really get under the hood and relearn to code.

1)  I want to master SCRATCH so that I can better teach it to my students, and so  that I know more of it’s potential uses (particularly in the elementary grades that I teach).

This spring my nephew got a rubiks cube.  When I was 13, I could solve a cube in under a minute, but I had completely forgotten how.  This spring I bought a couple of cubes and relearned how to do it.  I love problem solving puzzles (like sudoku) and I forgot how much I enjoyed the sheer muscle and brain stimulation of trying to solve a cube as quickly as possible.

The rubiks cube was left behind in a time in my childhood when I was also fascinated with the early personal computers (TI-99, apple II, and commodore 64 primarily).  From the time I was 13 to about 16 I programmed all sorts of things in BASIC, PASCAL, and a bit of assembly language.  I haven’t really programmed since, except for learning the basics of HTML and CSS, and the tiniest bit of Javascript.  I forgot how much I enjoyed programming.  Also as a podcaster, blogger, songwriter, creative-type 21st century internet denizen, I have come to realize that if you want to be more than just a consumer of media, you need to have a basic understanding of how to code.

2) I want to learn how to code again… not  just as a subject to teach but as a creative outlet for myself.  While I have been thinking about CCOW and doing the work of the workshop, I have also been investigating other ways to learn programming.  I have downloaded a bunch of `Teach Yourself Python` resources and I have signed up for the Android App Inventor site (which is based on scratch).

3)  I want to read more about and reflect upon Constructivist principles in my teaching and learning.  I have been enjoying some of the underlying philosophy behind SCRATCH and CCOW… alot.  I know that SCRATCH is based on a constructivist approach,  and I know that the facilitators have intentionally structured the course based on constructivist principles.  But I want to learn more about the basic philosophies, core principles, key writings and proponents, of the constructivist school of learning.

Given these 3 objectives here is a first try at framing a project idea:

I want to learn to code.  I would make the leap from Scratch to Python, which is a more multi-purpose language.  I could use it to code for the web or to make apps for my handy android phone.

So…  I will try to use a ‘How to code in python’ manual  as a guide to create a game in scratch.

In this way I will become familiar with some of the basic structure and syntax of python.  I want to use my growing knowledge of SCRATCH to make myself a rosetta stone to understand other programming languages– (like python).

 I need to dig into some online and downloaded resources, but I think I will try to use a tutorial on how to code a game such as reversi using Python.  If this looks too challenging to adapt to scratch I will choose a simpler game. 


My writing/thinking time is just about up for today,   When I revisit this post I want to flesh out my idea to get more specific about which python/scratch resources I would need and narrow down what game I want to make.  I also want to start to answer the Key Questions for Week 4- Workshop Project: Defining and Planning.


    1. Workshop project problem/exploration/question statement
      What is the problem you’re trying to address? Maybe it’s not a problem, but rather an area of inquiry to explore. What is the exploration or question that motivates your project? Can you express this in no more than 3 sentences?
    2. Workshop project format
      How are you thinking about responding to your problem/exploration/question? What will you be making or doing for your project?
    3. Workshop project needs
      What do you need in order to successfully make progress on your project? Do you have access to the resources that you need? What do you still need to figure out? Is it a big Scratch project, a series of mini-activities that explore advanced concepts, a proposal for a learning experience, new resources for young learners, or something else entirely?
    4. Workshop project plan
      What are the steps for getting your project done? What is a timeline for getting it done?
    5. Workshop project keywords
      What are five keywords or tags that describe your project?


Week 3 Roundup

This week has been quite busy at work with finishing report cards and all the end of the year assemblies and activities.  Just 4 teaching days and 1 PA day to go.

On to my CCOW activities this week.

Cumulative Activity: Games:  In this week’s “big project”, you’ll develop a game — a Scratch project that includes interactions between sprites, score, and levels.

Follow My Song

I was quite excited to try coding a classic pattern game like Simon.  I also wanted it to be a bit of a musical primer so I based the tones on a pentatonic scale.  The game does not have overt scores or levels but it does change in difficulty and speed as the pattern gets longer and longer.  This game is a classic.  Simple enough to need no instructions other than “Follow My Song”, but difficult enough to keep people wanting to play it more.

My imagination kept introducing `feature creep’   with ideas like making alternate costumes for the sprites like piano keys, guitar frets and flute and trumpet fingerings, and making a standard set of variables so that I could code a kind of framework or API to make music games using scratch.  In the end, it was enough of a challenge just to try to make compact, simple code to show the sprites, change their colors, and detect key presses and see if they match a pre determined pattern.  I ended up making 8 almost identical sprites (one for each note in a major scale).  I am pretty sure I could have done this using lists, multiple clones of one sprite, and variables to change the color and tone of each sprite.  In the end it was just easier to duplicate 1 sprite 8 times and change the code for each individual note.

Somewhere between the keypress and my broadcast to check it against the random list of the computer’s pattern, a glitch appeared in that it does not call game over until one press after you make a mistake.  Thus if you make a mistake on the last note of a pattern, you get to go to the next level.  I have not figured out how to solve it because I can’t find the error in my reasoning or in my code to check the pattern.

One of my third grade students told me that I should just say that this is part of the game, because it is fair to give people 2 chances.  I think I’ll stick with her answer, although the glitch is still bugging me.

Readings:  Illich, I. (1971). Deschooling society (Chapter 6). New York, NY: Harper & Row.

I have not had alot of time to flesh out my thoughts, but I’ve been thinking about how much Illych’s article on education webs foretold what we are doing here.  We have a MOOC with over 1900 members, from all over the world.  We are the self selected peer group, the facilitators are  expert support. We have wikipedia, coursera, and quick access to almost all academic literature, books, and media throughout history at our fingertips.   I think Illych would have quickly grasped the possibilities of the Internet for self-directed learning.   How else does our experience in this course resemble what Illych was describing?


  1. I made a post with this week’s Debug it activities on Sunday.
  2. Levels— I read through this activity and but did not do the assignment of looking for different ways people code levels using scratch.  I think I have a good handle on different ways to have levels in games with increasing speed, increasing difficulty, a change of scene or more adversaries with greater skills.
  3. Score:   In this activity, we needed to remix Fish Chomp by adding a score using variables.   Here is mine:


I added a countdown timer to make the game last for 60 seconds, and gave one point for each fish caught. I also added a global High Score Variable stored in the cloud. That means that you can compete against other scratchers for world bragging rights.

I added a Start Game broadcast for the purple fish because for some reason I had to press the green flag twice to get them to move and react with the yellow fish. It didn’t do that in the sample code, so I think it was something to do with my timer code or my if-then-else blocks.

Questions:     What is a variable? A variable is a letter or name that can have a “variety” of values.  Its value can vary.
 How would you explain variables to young learners?  I think that giving variables literal names like ‘score’ and ‘time-left’ can help them to make the connection between what is going on in the game and the idea of variables in math class.  I think the first time the concept of variables really clicked for me was when I was 12 or 13 and learning to program simple games in BASIC.  I think the same thing could happen using SCRATCH with young children.

4.  Interactions:  In this activity, we were given 9 specific tasks to try to code.  Here are my Interactions:


  •  Questions: Which puzzles did you work on?,       What was your strategy for solving the puzzles?     Which puzzles, if any, helped you think about your game project?

I got cute and tried to do them all in one project.  This was actually more difficult because some of the activities interacted with the others, creating more complexity.  After about 2-1/2 hours, I stopped with about 6 of them done.   Below each task I reflect on how I did it and answer the questions.

    • Whenever you press the B key, the sprite gets a little bigger. Whenever you press the S key, the sprite gets a little smaller.    This was pretty straightforward.  I programmed the cat to grow and shrink with these keys, and made it move with the arrow keys.
    • Whenever the sprite hears a loud sound, it changes color.  I did not do this one, but I have a pretty good idea how I would do it with the sensing blocks.
    • Whenever the sprite is in the top 25% of the screen, it says “I like it up here.”
      I made a sloping background and had the cat say this above about y 100.  The hardest part of coding this was the code to make sure the characters could not walk into the sky.  I did this with a `not touching green statement` so that it would also not walk through other sprites.
    • When the sprite touches something blue, it plays a high note. When the sprite touches something red, it plays a low note.
      I did not code this one either.  
    • Whenever two sprites collide, one of them says: “Excuse me.”
    • Whenever the cat sprite gets near the dog sprite, the dog turns and runs from the cat.
      I had the dog move towards the cat then turn a 180 and move back 50 steps.  It fulfils the task but makes for a yo-yo frenetic effect.
    • Whenever you click on the background, a flower appears at that spot.
      I used clones of one flower sprite.  When the stage is clicked it chooses a random color and size.  I also had a random location, then changed it to the position of the mouse pointer as per then instructions.
    • Whenever you click on a sprite, all other sprites do a dance.
      I did not do this, but I think I was going to do a loop with the whirl effect forward and back on the flowers.  I did end up using this technique with a looks block in my `Follow my song` game the next day so thinking about this challenge helped.
    • Whenever you move the mouse-pointer, the sprite follows but doesn’t touch the mouse-pointer.  At first I had the cat then the dog follow the mouse pointer, then I added the butterfly because it was tricky to add this code along with the other things I had the cat and dog doing.

Random Coding Fun

Last week, the facilitators introduced a change to the process of submitting and reviewing design notebooks.  Now we just need to submit the link to our design notebook (or noteblog), then choose peer notebooks ourselves from a numbered list of all the submitted notebooks for the week.  One of the participants on the forums requested a way to choose a random notebook on the forums.   kb8ywp used SCRATCH to code a perfectly useful, but visually plain  Random Notebook Number Generator

On a whim, I remixed it to add a bunch of randomly placed notebooks, and included a cloud variable which remembers when someone enters the number of notebooks for the week, so you only need to re-enter that number if it has changed.  My changes were mostly cosmetic, and not needed, but it made for a fancier Random Notebook Number Generator remix.

Here it is nearly midnight on a Friday night. I think my CCOW week 3 is finished. I`m looking forward to the next three weeks and my self-directed project, but I still have no idea what that might be. I`m sure something will come to me. And only one more week of doing both schoolwork and workshop work. Yipee.

Week 3 Debug It

DebuggingTime for Week 3’s Debug it activities.  I love how the facilitators use broken code to teach new coding concepts in this workshop.

Here are this week’s challenges.

  • Debug each of the five Scratch programs in the Week 3 Debug It! studio.
    • Debug It! 1
      In this project, the “Inventory” list should be updated every time Scratch Cat picks up a new item. But Scratch Cat can only pick up the laptop. How do we fix the program?
    • Debug It! 2
      In this project, Scratch Cat gets 10 points for collecting Yellow Gobos and loses 10 points for colliding with Pink Gobos. But something isn’t working. How do we fix the program?
    • Debug It! 3
      In this project, Scratch Cat is thinking of a number between 1 and 10. But something is wrong with the guess checking — it doesn’t work consistently. How do we fix the program?
    • Debug It! 4
      In this project, the “# of hits” display should increase by 1 every time the Scratch Cat is hit by a tennis ball. But the “# of hits” increases by more than 1 when Scratch Cat is hit. How do we fix the program?
    • Debug It! 5
      In this project, Scratch Cat is navigating a maze to get to the yellow rectangle. But Scratch Cat can walk through walls. How do we fix the program?

None of the challenges stumped me this week.  In fact I usually found the bug on my first pass through the code.   I think I have internalized many great problem solving strategies over the years.  But for debugging and when looking at code I tend to ask myself 3 questions?

  • What is this code supposed to do?
  • What is it actually doing?
  • How can I fix it?

This can then lead to:

  • How else can I fix it? 
  • Or: What is the simplest fix?
  • And: How can I change or extend the code from here?

I think it is important to teach children that in programming, as in life, there are many different ways to get to the desired outcome, and some are easier than others.

Here are my solutions and reflections on the challenges.

Debug-It 3.1 remix In the code for sprite4 (the laptop), it looked for when it was touching (sprite1– the cat) then disappeared and added the laptop to the inventory.
The code for sprite 2 (cheesy puffs) was looking for when it touched sprite 3 (the lamp) were and the code sprite 3 (the lamp) or was waiting to touch sprite 4- the laptop. Because only scratch moved, he only ever picked up the laptop. Solution– change the code blocks for sprite 2 and sprite 3 to look for when they touched sprite 1.

Tip– change your sprite names to descriptive names like cat, laptop, etc… so it is easier to see where there may be an error.

Debug-It 3.2 remix In the code for the yellow sprites, if it was touching the cat, there was a block that said to add 10 points to the score then hide. In the code of the pink sprites it said to wait for touching the cat then gave no further directions. I added the blocks to add -10 points to the score and hide the sprite to each pink sprite. Problem solved.

*Note to self. In the example they set up separate code for 6 pink and 6 yellow sprites. I think you could add more variety to the game, and less chance of bugs by using the clone sprite function and some random generators for to vary the number of each kind of sprite, their location, and even how often they appear on screen.

Debug-It 3.3 remix: Simple error. In the code checking if the secret number was greater than the guess it checked if it was < the guess. I just had to change the code block to if secret number > guess.

*note to self: I suppose I could have just reversed the conditions to ‘if guess is < secret#’ and that would have had the same effect.

Debug-It 3.4 remix: What was happening is that the hits kept incrementing while the ball was crossing Scratch for multiple hitcounts for each contact. I added a block of right after the hit count incremented and before the repeat. This made the counter increment only once for each contact.

Note to self: It would be neat if the ball bounced off of scratch when it hit him. One method I saw online was to add “point to sprite1” then “turn 180%” to have it bounce off the other sprite in a roughly realistic bounce. I think the accuracy of the bounce would depend on how large the sprites are and how scratch determines the location of a sprite. How does it do that? Does it use one of the outmost corners for the x,y value or a mean of the x and y values? I need to do some research and experimenting on this one.

Debug-It 3.5 remix:: I added this code to detect when Scratch is touching green walls. Forever {{If touching green then move -10 steps]}
*An alternate would be to only let him move if he is touching the white path. This would enable him to navigate a multicolored maze, as long as the path was white.

Week 2 Overview- Alice in Scratchland

Alice in Scratchland

When I first wrote this post, I thought I had completed Alice in Scratchland for the Scenes assignment of Week 2 of CCOW.  Then I went back and added Characters using {Make a Block} to define two character’s unique behaviours.  Then I added just enough puzzles and gameplay that players start to get drawn into Wonderland.  Then I added a final scene with an invitation to remix and continue the story.  So, In large part, this one project encompasses  over half of my week 2 activities.



This assignment was primarily to experiment how sprites and stage backgrounds can be used to change scenes in scratch.  I felt like I did this already in my About me project last week, but I gave it a go.  I went with an Alice in Wonderland theme.  Use the arrow keys to move around in the vignettes.

  What does the Stage have in common with sprites?   The stage has backgrounds, while sprites have costumes.  It is possible to change the appearance of each.   Stage Backgrounds differ from sprites in that they are fixed in place, and can have no motion or size effects.

 How do you initialize sprites in a scene?   You can hide them at the green flag until a certain background comes on or have them react to a broadcast command from the background or another sprite.
 What other types of projects (beyond animations) employ scene changes?   Games, especially 2d platformers, slide shows, digital story books, demonstrations and simulations.  Pretty much any application in scratch may use scene changes of one kind or another.
   How did others use backdrops in the studio?   To change colors or moods, to show pictures, to advance a story, or to show another screen in a game.

MartyH. made use of scenes and recorded narration to tell the wonderful story of Sadie and Fluffy.


The Make a Block Feature is a way to blend a variety of actions into one command unique to a sprite.  For my 2 characters, The White Rabbit and the Cheshire Cat, I used make a block to define those actions and movements that make the character unique.   The White Rabbit starts upstage left and moves toward the rabbit hole or the door with a distinctive double hop then step forward.  Randomly, he stops to say he’s late or other typical White Rabbit sayings.  I used a randomized list to mix up about 7 sayings.  Here is the script for the white rabbit.


For the Cheshire Cat, I used a costume of just eyes and the {ghost} effect, along with some random code to have scratch pop up anywhere on the top half of the screen at any time.   This gave the Cheshire Cat his characteristic feature of randomly appearing in the story.


Make a blocks are a great new feature of Scratch, which enables you to automate custom, repetitive or distinctive actions into one command.  This can make the rest of the scripts much more compact and easy to understand.  It is great for giving characters unique features, but it could also be useful to define certain algorithms or computations used as part of a larger program.  I can think of a teaching program for 2-d geometric shapes where you could define a block that would draw  each 2-d figure, ie) rectangle, square, octagon, etc…

Pass it On…  Remix Challenge.

It is nearly 150 years since Alice`s Adventures in Wonderland were first published and the story is beloved around the world.  I am interested to see where other people take my starter adventure with Alice and her companions (if anyone does take up the challenge with all the other potential remix projects to choose from).

 What is your definition of remixing?

As a folk singer, photographer, songwriter, elementary school teacher, podcaster, and recorder of public domain audiobooks (whew?),  I have come to realize that we stand on the shoulders of giants.  All creative endeavours borrow somewhat from the creativity of others before them.  I am passionate about the public domain and preserving this treasure of our forbearers which we can use to retell their stories, and remix to tell our own.   I try to use creative commons or public domain sources, such as open clipart as much as possible for these reasons.

How did it feel to remix? How did it feel to be remixed?

People are very proud of their work.  They can be quite protective of it.  But I have learned to let mine go into the world and see what stories it brings back to me.   For instance, here is a story from my songwriting blog a few years ago.  Take the time to listen to the podcast.  It is a great story.  (and it has an Alice in Wonderland connection too).

Filed by Sean on November-29-2009
 Special- King of Carrowocky [ 7:44 ] Download (5102)

This story is too random and too cool to fully explain.  Go ahead, try to explain the story in this podcast to your 1990 self.  I bet you can’t do it.  It began for me on November 24 when I received this tweet from Adam Gratrix @transpondency of theTranspondency Podcast.

RIAA’s Crafty King of Carrowocky mashup ft. @Sean_McGaughey Librivox reading of Jabberwocky.

Listen to the show to hear what happened next.

Links in this show:

Jabberwocky on

Mr. Fab: The Crafty King of Carrowocky

I love adding new words to old melodies or a new twist to an old story.  It is important to acknowledge and give credit to those whose work you build upon.    Having said that, I get sloppy about giving specific attribution for each of the images in my scratch projects.  I have to get better about that because I know how people who freely share their work love to hear back about how it was used.  I think I will go back into my projects and give proper attribution for the images.

     What are the opportunities and challenges with this activity for your students?  

Attribution is a huge one.  They just don’t understand or care about the issue of having permission to use images and media in their own works.

For my own remix, I chose: Jazzy the Outward Hound by rrtika.

I took rritka’s original concept, added a doghouse from and turned the story back on itself to change the ending?

It was interesting working with another person’s code. She handles turning around by making another costume. I just set rotation to left-right and point it in the other direction.

Here is my remix: Homeward Hound


Debug It

Earlier this week, I posted my Week 2 Debug It solutions.


Conversations Between Sprites: Week 2- Penguin Jokes

Week 2 Wrap-Up

This week I ran into several limitations of Scratch, particularly  when I wanted to enable cloud based lists to make a database of user submitted Knock, Knock jokes in the Conversations activity.  Then I realized that Scratch is not meant to be a robust, all purpose programming environment.  It is necessarily constrained and limited to introduce children to key programming concepts.  Once they develop an understanding of these general programming concepts, they can move on to other fuller-featured languages.


Conversations Between Sprites: Week 2- Penguin Jokes

The assignment:

Start by seeing inside the Penguin Joke project. Observe how the author animated the conversation between Penguin and Nano using wait blocks. Remix the Penguin Joke project to use the broadcast and when I receive blocks (instead of using wait blocks).

So I remixed it using broadcast blocks as per the assignment.
Then I wondered if I could combine some define your own blocks with a script and a list of data, and some loops to make a random knock, knock joke teller. So after the fish joke, Penguin starts choosing randomly from a list of knock knock jokes.

Then I got the idea that every few knock-knock jokes (25% randomly), penguin will ask the user to type in a knock-knock joke to be added to the list. I was going to try the cloud data feature to make a massive user contributed list of knock-knock jokes. Alas, the feature to have cloud based lists has not been implemented yet. It is still a good idea, and I like the added interactivity I added.


How would you describe Broadcast to someone else?
The Broadcast feature is a way for different elements of a scratch project (sprites, stage) to interact with another.  You can set up a broadcast for when a certain event or condition is met during the program.  Other sprites can listen for the broadcast then  {When I receive (command)}. they can carry out a certain task or script.

When would you use timing in a project? When would you use broadcasting? 

I would use timing when there are a fixed number of unchanging sequential events.  I would use broadcasting when there are a variety of possible outcomes that can come in sequential or random order.

P.S. I got some of my Knock Knock Jokes from

CCOW Week 2 Debug It

I’m loving these debug it activities. It is a great way to teach problem solving strategies and lateral thinking. It is also a great way to introduce need coding concepts.

2.1:  Original project: Debug-It 2.1 by karenb   My solution: Debug-It 2.1 remix

My Solution:
1st try- move define block code to stage… no change.
2nd try- copy define block code over to Gobo… no meow.
3rd try– drag sound “meow” from Scratch sound window to Gobo sprite icon. Success!

2.2: Original project: Debug It! 2.2 My solution: Debug-It 2.2 remix

My Solution:
The original counting code was set to always repeat (10).
I dragged the blue (answer) oval into the repeat block.
(And I added a trumpet sound when scratch is finished– Just because).

2.3: Original project:Debug It! 2.3 My solution: Debug-It 2.3 remix

My Solution:
The original code has no pauses after each talk statement and the broadcasts to call the other sprites are sent in no particular order.
Add a wait 1 second after each statement and broadcast.
Place the podcast block for each sprite directly after Scratch calls them.

2.4: Original project: Debug It! 2.4  My solution:Debug-It 2.4 remix

My Solution:
In the script for SCRATCH Cat after he say’s jump, I added a
[broadcast (jump)] block.

2.5: Original project:Debug It! 2.5 My solution: Debug-It 2.5 remix

My Solution:
This one was trickier.

I added a little script for each background:
When Background switches to (x) –> hide dinosaur — stop (all)–

For the auditorium block I added a show block just before the dinosaur.