Could also connect a bunch of locks and put all the keys on a key ring. Lots of pictures of latch, lock, etc ideas for montessori type preschool. This lock one could be made with 2 boards, some o-rings, and some locks from Dollar Store.
sensory balloon with matching cards. great for teaching 5 senses to preschoolers or keeping toddler hands busy! Except make balloons all one color, or else they'd memorize the color rather than rely on senses to determine contents.