Time and explanations of time seem to work differently for the very young. For Anthony (4), "yesterday" means any time in the past, whether he means half an hour ago or several months ago. As in, "I don't need to go potty. I went yesterday." (uhh...yeah, you need to go every day, Buddy.) Or, "Yesterday, we went trick-or-treating." (Probably not. Probably we only went on Halloween). Sometimes he doesn't even use words to indicate when in the past it happened, which is just as confusing, as in, "Daddy, we went to the fire station!" "You did? Really?" I have to translate, "Daddy, remember when we went to the fire station?" (It was at least 4 months ago when they were having an open house.)