If: Ball, Then: Catch

While you may think that you need a computer to program something, we are using many of the same skills every single day! In this activity we will learn about programming on paper.

What you’ll need:

• Printed template (printed single sided)
• Scissors
• Pencil
• A partner to check your program

 First, cut out the arrows and obstacles.

Next, place Sparky and Dot somewhere along the edge of the main grid. Then place some of the obstacles within the grid. It doesn’t matter where you place the obstacles, as long as there is at least one path between Sparky and Dot. Think about the story you want to tell; in my grid, Sparky has to make it all the way to Dot without running into the hedge, trees, or other robots. He also needs to focus and not let the balloons distract him from his mission!

Now, place the arrows to mark a path between Sparky and Dot. When you do this you are using a skill called “decomposition”. This is when you break down a big problem (e.g. moving Sparky all the way to Dot) into smaller problems (e.g. one step at a time).

Now you will use the arrows to help you write your program. Using the template, write out each movement (right, left, up, or down) one by one. An example program is below.

Now you need to test out your program. To do this, remove the arrows from the grid. Give your program to a partner, and have them follow it step-by-step by placing the arrows back on the grid. If it works, great! If it doesn’t, go through the program together and try to figure out what went wrong. Fix your program and try again. In programming, this is called “debugging”, and it happens all the time!

Once you are finished, you can swap roles with your partner. You can also make the challenge harder by:

• Adding more obstacles (maybe draw your own!)
• Adding a bonus challenge (e.g. pick up the ball along the way, talk to TC, etc.)
• Making a bigger grid

We hope you enjoyed this activity! It was inspired by a seminar from Let’s Talk Science, a wonderful STEM outreach initiative in Canada. We’d love to see a photo of your creation or hear your feedback in the comments! This activity is based on the book If: Ball, Then: Catch.