Cut the neck off the balloon and discard it. Stretch the balloon over the mouth of the jar and secure it with the rubber band.
Tape the needle or pin, point facing out, to the end of the straw. Use a generous pool of glue to attach the other end of the straw to the center of the balloon.
Prop the cardboard against a wall with a fairly constant temperature and set the jar just in front of it, but not touching. Label "high" and "low" as shown. Mark the spot at which the needle now points. Check the barometer every few hours and mark the changes on the board.
Why it works: As weather patterns shift, the air pressure around the jar changes, while the pressure inside it remains the same. As the pressure outside increases, the balloon is pushed down, forcing the needle up. As the pressure outside falls, the balloon swells, sending the needle down.
Welcome! I am Mrs. Timbrook, currently an elementary school substitute teacher. I am very anxious to have my own classroom to teach wonderful and exciting things to my students! I disclose there may be affiliate links throughout this blog. All money earned goes towards buying supplies.
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