Common household items that are either circular, square, or triangular.
Get a bunch of household objects that fall into 3 shape categories -- circle, square, and triangle. For instance, you can use a wallet, a coin, a ball, a piece of bread cut into a triangle shape, a tomato. Once you have many objects, about 5 of each shape, put them on a table and ask your child to sort them by shape. Great both for sorting and shape recognition.