A.G.
Have different bins or pans or shallow buckets of unpopped corn kernels, dried beans, flour, and even things like q-tips.
Fill socks with corn kernels, rice, buttons, macaroni, cotton balls, coarse salt - anything small and have them toss it to each other.
Fill pieces of tied up cheesecloth with different spices (keep them in different ziplocks).
Tape pieces of colored cellphane (blue or red stimulates the brain in this activity) between two paper frames glued to a popsicle stick and have them cover one eye while looking at different things.
Fill a bin with cut up straws of different sizes cut in half, quarters, thirds and so on.
I liked to place toys like marbles in the freezer and let my son feel a room temperature marble and then a frozen marble. I used matchbox cars and legos.