Classify each of the following objects as either heavy or lightweight: bubble, aircraft, bear, mouse, bus, raisin, strawberry, popcorn, elephant, piano, plastic cup, train, butterfly, whale, refrigerator, feather, pencil, ship, tree, flower.

Heavy weight objects include: aircraft, bear, bus, elephant, piano, refrigerator, ship, tree, train, whale.
Lightweight objects include: bubble, butterfly, feather, flower, mouse, pencil, plastic cup, popcorn, raisin, strawberry.