Skip to Content

Asteroids and Little Crab Projects for K-12 after school computer club

Students are responding that they like spending class time creating games with Scratch. This post includes slides for 2 games we're making in class using Scratch.

 Here's what we've been doing in Computer Club as of late.  We typically have at least 3 sessions.


1. The Computer - the first one introduces computing in general, and we talk about machine input and output, similar to what was posted on The lesson plan for that meeting is attached below, "Computer Club Lesson 1 - The Machine-1.pdf"  We were fortunate enough to have real (but older...) computers for the students to tear into and identify parts and map that back to what's going on for input and output, what the parts are used for and so on.  If you don't have that kind of resource available, you can probably use a site like to discuss pieces and parts and relate that back to what the students are using for Scratch.


2. Scratch Introduction - the second one introduces using Scratch for students who haven't used it before.  The project itself is less critical, we simply want the students to gain familiarity with dragging and connecting scratch blocks, and have some fun along the way so we include sounds, movement, and different costumes.  Even better if the students can record themselves for the sounds and take pictures of themselves or others for costumes using a webcam.  But even if all you have is Scratch installed, there are plenty of sounds and sprite images to work with.  The lesson plan for that meeting is attached below, "Computer Club Lesson 2 - What is Scratch.pdf" and the resources can be anything including the videos on or the Scratch card document or the Scratch Reference Guide document.  The point is exploration and less do-exactly-what-I-do instruction.  If the students have successfully made a scratch project that incorporates at least some movement blocks, some sound blocks, some control blocks and likely responding to keyboard events, they've at least got a handle on using Scratch for now.


3. Scratch Game Development - the third one is more of a do-what-I-do instruction session where we build one of two games, depending on the grade level.  The lesson plan for that meeting is attached below, "Computer Club Lesson 3 - Scratch Game Development.pdf" and the 2 different games we've been using are attached below:

    - ScratchLittleCrab01.pdf - this is a Scratch version of the scenario used in the Greenfoot workshop, resources are available at and that's an excellent follow-on if you get into wanting to do the projects using Java and Greenfoot rather than Scratch.  But that's down the road.  I've re-packaged the sounds/images we use as "" below in case you don't want to dig those out of the Greenfoot project structure.  Again, you can use any sounds / sprites that come with Scratch if you don't have access to the web.  I made the crab, worm and lobster images move slightly if you use the "next costume" block in the Looks category, so you may want to use those or if you have the time, you may want to work with the students in creating their own series of stop animation ready sprite costumes.  This project is easier than the Asteroids project below so you might want to gauge which of these makes better sense for your target audience.


    - ScratchAsteroids01.pdf - this is a Scratch version of the Asteroids game.  The idea was that most kids will have already played some form of flying-around-and-shooting game and if not you can always have them look up asteroids projects on to get the idea.  This one also has a nice counterpart over on where if you download the "book scenarios" and load them up in Greenfoot, one of the projects is a good Asteroids scenario.  This scenario is more involved and spends more time motivating the math portion of moving around, going off screen and maintaining a momentum vector so that the rocket ship glides around smoothly.


  So far, survey results have been positive.  For our last class, we had these results:


Q: Did you enjoy Scratch?

1 No, it was too easy to use

1 No, it was too hard to use

4 Yes, it was challenging to use

1 Yes, it was easy to use

9 Yes, it was fun to use


Q: Did you enjoy this after school activity? (scale 1 to 5, 5 means they enjoyed the activity)

1 - rated it a 3

5 - rated it a 4

10 - rated it a 5


Q: Would you recommend this activity? (scale 1 to 5, 5 means they would recommend the activity)

1 rated a "1"  but also said "it was too easy to use"

3 rated a "3"

2 rated a "4"

10 rated a "5"


Q: Would you join us again?

0 rated no

7 rated maybe

9 rated yes

Ed Shields

I like the format you have presented in the lesson thanks. Especially "Essential Question" and "Big Idea" I like to take a similar approach to my lessons. I find YouTube is a great source of short videos on topics that I play for the kids in the beginning of the lesson to facilitate discussion.  I am a computer engineer and I like to spend a little time exposing the kids to the history of computers, the history of video games, etc. and there are many videos on YouTube that address these subject. I will compile a list and follow up with a seperate post. Thanks!!

Daniel Green

 Thanks, Ed, that would be very helpful!  One source for this sort of thing I've found to be quite target rich is one of the "Computer Science Principles" ( pilots at Berkeley, the "Beauty and Joy of Computing - CS10" course which has webcasts you can subscribe to in iTunesU or on their web site (