Some safe science experiments for sixth grade students include using static electricity to bend water and making invisible ink. Another involves making lava blobs in a cup.
To create static electricity, students comb their clean, dry hair 10 times. Holding the comb to a thin stream of water from a faucet bends the water towards the comb. Students can experiment to find out whether water temperature affects how much the water bends towards the comb, whether the comb size or material affects the bending, and whether moisture in the room's air affects it. They can also try the test in a steamy versus a dry room.
Making invisible ink involves mixing 2 tablespoons of clear vinegar with a few drops of water in a bowl, then dipping a small cotton-tipped stick into the mixture and using it to write a message on a piece of white paper. When the paper is dry, the message becomes invisible. Holding the paper under a heated light bulb makes the words appear because the heat from the light bulb causes the clear vinegar to oxidize and turn brown. Students can compare the effects using honey, lemon juice and milk.
To make lava blobs like those in lava lamps, students fill a clear glass three-quarters full with water, then add five drops of food coloring. Next, students slowly pour in some vegetable oil, observing how the oil floats to the top. When they sprinkle salt on top, oil blobs start moving up and down in the glass. Students can continue to add salt, testing how long the effect continues. They can try other glass heights and other kinds of oil and substitute sugar for the salt to see if these change the effect.