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
Instead of numbers write the color word on the bottles. Sort pom-poms by color. Empty each bottle and count the pom-poms. Then record how many pom-poms were in each bottle. Add the two colors together for addition practice.
Two preschool math activities using Duplo Legos. These are great for younger brother while the older ones do their schoolwork! Identify the next number in a series of numbers up to ten. Pre-school age 3 and 4
I think you could also have multiple pipe cleaners coming from one number and students have to show multiple ways to add numbers to get to that number. Counting with pipe cleaners and beads. Great for fine motor development too.
Toddler activity with playdoh, spaghetti noodles and cheerios Also dumb. I don't know a toddler who won't break that noodle.and eat the Cheerios. Good for fine motor skills and keeps them busy for a long time!