Materials Needed for Activity Blue ice water Red hot water Meter tape Marker Straw plastic cups

What To Do

• Make marks 5 cm and 10cm from the bottom of the straw.
• Fill one cup almost to the top with blue ice water. Fill another with red hot water.
• Place the straw down to the first mark in the blue water. Put your finger over the top of the straw. Lift the straw out of the water.
• With your finger still on the straw, put the straw down to the second mark in the red water. Lift your finger off the straw so that the water in the straw will rise. Place your finger back over the top of the straw and lift the straw out of the water.
• Observe the two colors of the water in the straw.
• Place the straw in the empty cup. Lift your finger to release the liquid.
• Have another member of your group repeat steps 3-5,placeing the straw in the red water first and then in the blue water.
• With your finger still on the straw, slowly tilt the straw so that it is almost horizontal. Observe what happens.

What Happened?

• What happened when you put the hot water in the straw first?
• What happened when you put the cold water in the straw first?
• What happened when you tilted the straw?

What Now?

• Which water is heavier? Give reasons for your answer.
• Why did the water react differently depending on the order of the cold water and the hot water in the straw?
• What would you expect to happen if deep ocean water became warmer than the water above it? Why?