One of the nice things about geometry is that it's all around us. The lesson presented here has elementary schoolers go out to the playground to identify and name a variety of geometric shapes. They perform a "geometric scavenger hunt" of sorts. The teacher can request that they find a specific kind of shape, or allow them to identify as many shapes as they can. After a teacher-led discussion which reviews basic 2-D and 3-D shapes, learners go out and see how many they can find. I love lessons like this that get kids outside, and have them find real-life examples of mathematics!