Any room in the house can double as a learning center for readiness for kindergarten activities. This time, science takes a bath (in either the tub or the sink).
With a little water and several containers and bottles of different sizes, let your child experiment with how much water it takes to fill them up. Figuring out volume, that is how much something can hold, is much more challenging than figuring out long/short or wide/narrow. This is a concept that kids work on at school long past primary grades (and is even tricky for adults). But it starts with babies discovering that spaces can be filled and grows as toddlers experiment with the concept that some containers hold more than others.
Lots of water play science and discovery now before children go to kindergarten makes learning about volume much easier to grasp. Kindergarten readiness in a bottle, no genie needed.