Had when i worked in a preschool and kids love them! I would use colored sand instead of white salt. DIY salt tray with alphabet cards. Easy to make and kids have fun smoothing out the salt after correctly making the letter
Make "Sponge Bombs" and gather some neighbourhood kids (and adults) together along with a few buckets of water for a fun water fight. unlike water balloons you won't have pick up a ton of shriveled latex balloon pieces afterwards.
Cinnamon in the Sandbox--- Did anyone else know this? Now that its getting warmer, the kids are going to want to play in the sandbox. Cinnamon in the Sandbox keeps the bugs away! I knew cinnamon repelled ants. but I never thought of this!