Kids are born researchers. Everyday Science Experiments
- Bowl of water
- Paper towels, cut into strips
- 3 or more different markers, including black (non-primary colors work best)
The Method Draw a wavy line an inch from the bottom of each towel strip, using a different color pen on each. (Older kids should note which color is on which strip.) Dip each strip into the water so that the bottom edge of the paper towel is submerged, but not the line of ink; hold in place as the water creeps up the towel. The ink marks will spread, revealing the different dyes that make up each color.
- Smooth surface (like a table)
- 1 balloon (uninflated)
- 1 water bottle sport-top
- 1 old CD or DVD
- Duct tape
The Method Glue the bottom of the sport-top over the hole in the CD; let dry. Seal the bottle top’s base with duct tape, covering the glued area so air can’t escape. Stretch the balloon over the spout. With the sport-top open, inflate the balloon by blowing into it through the hole in the CD. Then click the top shut so the balloon stays inflated. Set your creation on a table and gently pull the sport-top open. The air coming out of the balloon will lift your craft; give it a push to send it zipping across the room. Next try pushing the hovercraft while it’s deflated. Notice that it moves more slowly.
The inflated balloon wants to shrink back to its natural shape; since it isn’t sealed, it pushes air out of the hole in the CD. The force of air escaping lifts the CD, so it hovers above the table, says David Epley, aka Doktor Kaboom!, star and creator of the science DVD Try This at Home. It’s a simple lesson about friction. Why does the craft move faster when the balloon is inflated? “Putting the air between the CD and the table keeps them from rubbing against each other, which slows things down.”