Fine motor control
Fitting shapes into holes is fiddly. You need quite a bit of control. That’s why shape sorters for the youngest children have generous openings and simple shapes.
Bringing fingers and thumb together to grasp each piece develops the hand strength and dexterity that will later be needed for confident pencil grip.
Spatial reasoning
Which way round does it go? This way or that way? Fitting a wooden hippo into an ark doesn’t sound like an essential life skill but this kind of spatial reasoning is crucial for reading. Is that a ‘p’ or a ‘q’, a ‘b’ or a ‘d’? Learning to orientate objects in space is the first step - and lots of fun, too!
Sorting and matching
Sorting means grouping things together that are the same. Two lions, two cats, two zebras. Matching, counterintuitively, is the opposite: what is different about these two things. Put two shapes side by side. Do they match? You are looking for differences between them. Find a difference? No match.
So a shape sorter is really a shape matcher. Is this the right shape for this hole?