Disappearing water
Objectives: Students describe in writing how two cases with a single difference can show cause and effect. Students use subtraction of collected data to represent visual observations. Students describe verbally how wind increases evaporation.
Materials:
Two bowls
plastic wrap, like Saran Wrap
water
pencils and journals or paper.
measuring spoons
Procedure:
Put a small piece of tape on two bowls to label them ‘A’ and ‘B’. Fill each bowl with 5 tablespoons of water. Put plastic wrap over A and not on B. Students record in journals how much water was poured into the bowls. Which one will dry up first? Students write predictions with explanations and/or speculation. A few days later read the predictions again. Pour out the water from each into a measuring cup and compare the two amounts.
What was the only difference between the two bowls of water when we started?
Why are the two different now?
All the water in bowl B evaporated, We know it had 5 tablespoons. There’s zero water left. 5 tbs - zero left over = 5 tablespoons evaporated.
5 - 0 = 5
Measure bowl ‘A’ . It may still have all five tablespoons. We know it started with 5 tbs. 5 - 5 recovered = 0 evaporated. Sometimes I did this experiment and I could get 4 tablespoons out of the dish but not enough for the last one. In K through 2nd we say the last one wasn’t a full tablespoon so it doesn’t count. 5 - 4 recovered = 1 tbs. evaporated.
Where did the water go?
Close:
Why did the plastic wrap keep water from evaporating?
What did the air in the room have to do with it?
How did the numbers we wrote in our journals show what we saw with our eyes?
What are some other ways we could use writing to remember details?