Magnetic number fishing, they add what they catch! As well as addition, develops hand/eye coordination, fine motor--I love this for magnetic letter fishing too! When they catch a letter, they say its name and sound.
Shaving Cream Blocks: an easy toddler activity building with shaving cream and block. A great preschool activity that's easy to set up. Kids Activities Sensory Play Toddler STEM STEAM Engineering for Kids