If you want a simple way to measure altitude to show how air pressure can reflect height, but do not want to go to the considerable expense of buying a real altimeter, you can make your own. With just a few items, many of which you will have around the house, you can make a functioning altimeter that won't be accurate enough for aeronautical use, but it can measurably demonstrate height.
Make a hole in the orange juice container's lid just large enough to fit the clear plastic tubing through.
Push the plastic tube through the hole so that about six inches of the tube extends through the bottom of the lid; place epoxy glue to seal around where the tube enters the lid to make an air tight seal.
Screw the cap back onto the orange juice container and bend the plastic tubing as shown in the diagram.
Attach a 3x5-inch index card, using rubber cement, onto the front of the orange juice container behind the bottom of the plastic tube.
Color 1/4th cup of water with enough red food coloring to make the water bright red.
Tape the bottom of the plastic tube to the orange juice container on each side of the 3x5 card.
Use the eyedropper to put enough drops of red water into the end of the tube to make an airtight seal inside the tube.
Place your new altimeter on a tray and carry it to the lowest point in your house or building. Make a mark on the 3x5 index card to show the water line.
Go to the highest place in your house or building and check where the red liquid is at now and make another mark. Calibrate your altimeter by making marks for different heights.
Have some fun and take you altimeter to a large high-rise building and watch what happens when you take an elevator ride. Make sure you place your altimeter on a tray or some other type of carrier where you can watch the liquid rise and fall.
Do not make any sharp bends in the plastic tubing because you will inhibit the flow of air. If you touch the handle or any other part of the orange juice container, your body heat will affect the results.