The teacher was asking the child to copy the instructions on the cards by putting the correct number of balls or blocks in the correct jars.  Personally, I thought this was really complicated as it was asking the child to consider multiple aspects of a problem at once.  I can’t imagine that many children 4 and under would be able to successfully complete this task without a lot of instruction and support.

As a manipulative that children can explore on their own, I think this kit is fabulous.  The materials are really satisfying- the blocks and balls are small and fit into the palms of small hands, the lids have holes in the top so the items can be dropped in, and the jars are see-through, so children can see what is happening inside.

If I were to use this manipulative in a more didactic way, I might ask a child to place a certain number of items in each jar (one aspect to consider at a time) or to only put balls in a jar (one aspect to consider at a time).  For older children, adding one more dimension to the task (i.e. “Put three blue items in a jar” or “Put red balls and blocks in a jar.”) would also be appropriate.

Truthfully, I think children might find much more interesting ways to explore this one on their own.