"plus sign"

The other day Joel had his yearly doctor check up, eye exam and Kindergarten shots. When he found out he had to get shots he told me he might cry 1 tear or 3 tears...well guess what!? He is proud to say he cried "0" tears! During his eye exam he was reading off the pictures and shapes just great...circle...boat...heart...star...big...house. Wait, "big?" I looked up at the sign and every time the nurse would point to a + sign he called it a "big"! HAHA Well I guess that is something we haven't went over. I know he knows math facts like 1 plus 1 and so on but why he calls it a big I have no idea! I asked him after his appointment and he said, "because it makes things big". Well I suppose that's true!