A couple of days ago, I purchased a box of assorted buttons at a craft store. I didn't have anything specific in mind for them, other than that they'd be a fun manipulative for the kids (and for me!) to play with. Besides, they're pretty. :)
Jonathan and Thomas have enjoyed sorting through them, finding their favorites, and arguing over possession. They've strung beads on thread,

turned them into a bracelet,

and learned how to sew them onto a piece of felt.

They're having a good time.
Josiah, now...Josiah is in love with the buttons.
In love. He wants to touch them, play with them, (eat them!) let them slip and slide through his fingers and fall on the floor. He sorts them, sometimes by color but usually by some method invisible to me. He pours them back and forth between cups and bowls and measuring cups.

This afternoon he spent a full
hour doing this. Life went on around him, but he was utterly oblivious to it. About 30 minutes into this activity, Thomas' attempt to take some buttons was met with cries of outrage - but once Thomas was removed from the scene Josiah went right back to pouring buttons.
Sixty-five minutes after starting, he put all the buttons back into their box and asked for lunch. Whatever he'd been working on was apparently finished.
Reading about educational theories and child development is interesting...watching it play out in your very own child simply fascinating.