- Cut three holes in side of the soda bottle.
- Stack the pennies into three piles containing 4, 8, and 12 pennies.
- Carefully wrap stacks of pennies with foil.
- Place a rubber band around the plastic bottle and slide it next to the closest hole. Position the other rubber bands next to the two remaining holes.
- Place the four-penny stack under the rubber band closest to the bottle's top.
- Place the eight-penny stack under the middle rubber band, next to the middle hole.
- Place the 12-penny stack under the last rubber band (NOTE: The weights should be next to the holes NOT over them.)
- Push the shorter end of the straw (about 1 inch) through the hole in the bottle's cap. Reattach the bottle cap to the bottle. Keep the flex section outside and bent upwards. Tape straw securely into place in bottle cap.
- Lower the "submarine" into the water. Do not let long end of straw take in water.
- Observe the action of the "sub" and record your observations.
- When the sub stops sinking, blow into the straw.
- Observe the action of the sub and record your observations.


