Index Cards
Parents know just how much kids go through packs of index cards during exam season. You can buy index cards at the dollar store for only 50 cents for 100 cards, or you can choose to spend $6 for 12 packs if you prefer buying in bulk.
Flashlight
Although dollar store flashlights would not be strong and are not of the best quality, these mini flashlights would come in handy if power happens to go out. They also come with a keychain, which makes it easy for you to carry around all the time. They are also very cheap, so there is no reason for you to not get one.