@jessmahler Yay! And then if you need to show the difference, performing things he can't see but can know happened - like showing a piece of paper, bringing it under the table, folding it in half, then bringing it back out - can give him chances to think about the difference between "happened" and "perceived". Be careful, he's going to get really fascinated with figuring out things he can't perceive and suddenly 20 years later he has a microbiology degree