Some interesting science projects include creating an electromagnet out of a battery, copper wire and an iron nail; making a lava lamp out of a soda bottle, vegetable oil and a fizzing tablet; and making an egg float in water with salt.
To make an electromagnet, wind the copper wire around the iron nail and leave two ends of the wire jutting out. Attach these ends to both ends of the battery and it's done.
To make a lava lamp, pour water and vegetable oil into an empty soda bottle. Wait for the two liquids to separate then drop a fizzing tablet. The oil should start floating around, forming blobs.
To make an egg float in water, pour water into a cup until it's half full. Mix this with salt, then pour normal water on top. Slowly drop the egg and it should float in the middle of the water.