The weather was beautiful. It was shape and color day. I had an activity planned, but it was for indoors and I didn't want to be inside and neither did the kids. So, I did an impromptu chalk shape game.
I drew large shapes on the ground in chalk. I did every basic shape I could think of. I then called out a shape and had my kids run to it. I didn't think my five year old would like the game at all (too easy) but he played along. It really worked well with my two year old. She doesn't have every shape down yet, and following big brother around helped her learn more about shapes. If you have a toddler and no older siblings, you can definitely run around with your toddler.
You could also draw multiple shapes all over the driveway for multiple children if you need to make it more challenging.