A vacuum cleaner is able to suck dirt off carpet because high pressure air from outside it flows toward low pressureair inside. In an electric vacuum, a fan causes air inside the vacuum to move quickly, which lowers the air pressure,causing suction. The higher-pressure air from outside the vacuum is sucked in to replace the low-pressure air,bringing dirt and dust with it to be caught in the filter bag. (Learn more about how vacuums work here.)In this project you can make a hand-pump vacuum cleaner that alters the air pressure inside it and creates suctionusing a piston instead of a fan. Follow the procedure to make your vacuum, then read the explanation of how itworks! An adult will need to help with the cutting.Materials: 2-liter plastic soda bottle Ping-pong ball Razor blade, box cutter, or sharp scissors Tape Thread Paper Tissue paperProcedure:1. Cut the bottom of the soda bottle off about 1/3 of the way up from the base. Now cut a slit down one side of thebottom third of the bottle - this will allow you to slide it inside the top part of the bottle so it can act as a piston.2. Cut a 6"x3" strip of paper and fold it in half lengthwise for extra strength. Tape this strip to the bottom of the bottleto make a handle for your piston.3. In the top part of the bottle, cut a 3/4-inch hole about 1-1/2 inches below the neck. This hole will lead to the filterbag.4. Make a filter bag for your vacuum with a 6"x4" piece of tissue paper. Fold the paper rectangle in half and tape thesides to make a bag. Tape this over the hole you made near the neck of the bottle.5. Tape one end of the thread to the ping-pong ball. Put the ball in the top part of the bottle. Feed the free end of thethread through the mouth of the bottle, and tape it to the outside of the bottle so the ping-pong ball hangs just slightlybelow the neck.How does this contraption you just made work? Push the bottom part ofthe bottle into the top part, then pull it back sharply. This decreases the airpressure inside the bottle, because now there is a bigger space for thesame amount of air. The lower-pressure air inside the bottle createssuction, pulling in higher-pressure air from outside in through the mouth.Now push the piston back in; this compresses the air and increases thepressure, so air flows back out of the bottle. The ping-pong ball works as avalve - when you push the piston in, it forces the ball into the neck of thebottle so that the air exits through the hole with the filter bag, rather thangoing out through the mouth.Now put your vacuum to work! Try sucking up bread crumbs or tiny ballsof paper. When you pull the piston out, they will be sucked into the bottle, and when you push the piston in, they willbe forced into the filter bag.Experiment to find out the best way to use your bottle vacuum. Does it work better to pump the piston rapidly? Shouldyou pull out on the piston faster than you push in on it? Can you think of ideas to improve the design and efficiency ofyour vacuum? Give them a try!