What are some fun things to do with a 20 month old?

My son is also 20 months and very active. He loves to play outside, and I don't let the heat deter us too much -- kids are quite resilient. Just make sure to apply sunscreen regularly and offer lots of water and frequent rest breaks. My son plays outside most days, and on the hottest days we play in his baby pool or fill a large tub with water and splash in it, or run through the sprinkler, or throw water balloons, eat popsicles, etc. On rainy days we play inside, and he likes to help around the house (everything is a game to a 20-month-old, including folding laundry, sweeping the floor, dusting, etc), or we do puzzles, color, build and knock over towers of blocks, roll back and forth on the floor, etc. He also likes pouring things from one container to another (either water, in the sink or bathtub) or solid things like rice, sugar, etc. It's messy, but if you can keep it contained they love it! Good luck and have fun!