Log in or register to comment Reflect on using the collision block and the count-within block in the Colliding Turtles activity. Computer Science Concepts Comments While I didn't use the "count-within" block, I really liked the potential introduced by the "collision" block. It brought me back to my childhood memories of tag and I got excited with using different agent shapes. I only wish I was able to add new agents and change the shape of the starting turtle. Once I can do that, I can simulate a game a true game of sharks and minnows! I can't wait to learn how to introduce multiple agents! In my challenge, I did not use the "count-within" block. I am wondering what real-world scenario would that block be applicable. I am fond of the collision block; it will help in alerting my students of a change in their simulations. Log in To Post New Content in the Forum.