Everyone has items that need batteries, but there comes the time when the batteries die and the item gets forgotten.
A cool idea for kids or teens (or anyone) is go through their room and collect all the items that need new batteries again. Go out and get them new batteries, you can wrap up the batteries by them self or put them into the item and wrap up the item again as a surprise.
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Another idea is go through the room and find items that need repair, or cleaning, or new parts. Give an old favorite new life again.