# Start here!

Overview of this topic.

# Welcome to Crowds!

## In this topic we'll explore how swarms of robots were created for WALL-E using combinatorics.

### This topic contains two lessons:

**Appropriate for grades 4-7****Use combinations to create your own cast of robots of a given size**

**Appropriate for the high school level****Explore how combinations and permutations leads us to the binomial coefficient when casting scenes**