Cranberry Craze

Pre- Activity

• Have students name different foods that we eat during the Thanksgiving holiday. Ask them if they can name ones that might be pollinated by insects. Write the list of names items on a white or chalkboard.
• If cranberries (cranberry sauce) is not named, point out that it is also a Thanksgiving food. Ask students if it’s a fruit. Ask them why it is a fruit (it has seeds inside).
• Explain how cranberries are pollinated.

Floating Cranberries

• Pass out the worksheet for students to answer questions as they go along.
• Have students make a prediction about if dried cranberries will float, have them record their answers in the worksheet.
• Place dried cranberries in a glass of water. They should sink to the bottom.
• Now have students make a prediction about if fresh cranberries will float, have them record their answers in the worksheet.
• Place fresh cranberries in a glass of water. They should float on top.
• Have students explain why they think the berries floated when they were fresh but not when they were dried.
• Cut open the fresh cranberries to reveal pockets where seeds are, and also air. Explain that the air pockets are what helps keep the berries floating, but when the berries are dried the air is displaced causing them to sink.
• Talk about how the cranberry's ability to float helps with them being harvested.

Dancing Cranberries

• For an extra fun little experiment make cranberries “dance”.
• Place dried cranberries into a glass of water. They will sink to the bottom like before.
• Now add vinegar and baking soda to the glass. The cup will foam over and cause the berries to rise and fall repeatedly.
• Explain that when the cranberries mix with the carbon dioxide gas, they get pushed upwards. When the gas bubbles pop, the CO2 is released and the berries drop. This process repeats for some time as a lot of CO2 is produced in the vinegar baking soda reaction.

Background:
Many of the foods we enjoy during holidays come from plants that must be pollinated. Some of these include squash, pumpkins, apples, celery, broccoli, and even cranberries. Cranberries grow on low shrubs with dark pink flowers. These flowers rely on bees to pollinate them. After pollination occurs and fruits are made, they can be harvested. Cranberries are harvested by flooding their fields and using specialized machinery to detach them from their stems. The berries float on top of the water, allowing them to be easily collected.