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Cut the neck off the balloon. |
 |
Paint the jar's rim with rubber cement. |
 |
Strech the balloon over the mouth of the jar and hold it flat with the rubber
band. |
 |
Snip the end of the straw at an angle so that it forms a sharp point. |
 |
Tape the straw to the balloon so it sticks out to the side of the jar. Make
sure the taped end is near the middle of the bottom, not the edge. |
 |
Using the rubber band and rubber cement, seal the balloon so no air can
get past it into or out of the jar. |
|
|
 |
Tape the jar to the piece of wood. |
 |
Stand a ruler against the wood near, but not touching, the straw. Tape it
firmly to the jar so it can't slip. |
 |
Put the jar somewhere in the room where the temperature will stay the same:
not near a heater or window. |
 |
Look at where the straw is pointing on the ruler. Write down the measurement
and the date. |
 |
Record daily the markings on the ruler. |
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