Bubbles in Water
Brian and Joe are looking at the water boiling in the pan on the stove.
Brian says that the bubbles are made of air that gets pushed out of the water when the water gets hot.
He argues that he knows that there is air dissolved in water because fish are able to breath the oxygen in the water.
Joe says that the bubbles are made of water that has turned into a gas — water vapor.
Joe agrees with Brian that fish are able to breathe oxygen in the water. But the pan has been boiling for 10 minutes and it is still bubbling just as much as it was at the beginning. If Brian was right, wouldn’t the air be gone by now?
Note: The numerical scores indicated in the scoring rubrics were for research purposes. Higher scores indicate higher quality argumentation. We encourage you to use a scoring scheme that matches your present goals for students.
1 What idea is Brian arguing for?
…
| Level | Description | Student Responses |
|---|---|---|
| 1 |
Student answer refers to “air.” |
air is dissolved in the water that there is air in the water |
| 0 |
Student does not identify Brian’s argument. |
bubbles pushing out of the pan bubbles |
2 2. What is the reason Brian gives to convince Joe that he is right?
Select A, B, C, or D
- Fish are able to breath the oxygen in the water
- Bubbles are made of air
- The pan has been boiling for 10 minutes and it is still bubbling
- Hot water boils
| Level | Description | Student Responses |
|---|---|---|
| 1 |
Student selects A. |
|
| 0 |
Student selects B, C, or D. |
|
3 What idea is Joe arguing for?
…
| Level | Description | Student Responses |
|---|---|---|
| 1 |
Student answer refers to “gas” or “water vapor.” |
Bubble turned to gas bubbles in water is gas |
| 0 |
Student does not identify Joe’s argument. |
how it affect the it TODO: ^^ is this complete
When water gets hot, it bubbles |
2 2. What is the reason Joe gives to convince Brian he is right?
Select A, B, C, or D
- Fish are able to breath the oxygen in the water
- Bubbles are made of air
- The pan has been boiling for 10 minutes and it is still bubbling
- Hot water boils
| Level | Description | Student Responses |
|---|---|---|
| 1 |
Student selects C. |
|
| 0 |
Student selects A, B, or D. |
|
Brian says that he knows that water is made of hydrogen and oxygen. The bubbles are caused by the water breaking down to produce hydrogen and oxygen that are both gases. These form bubbles like the gas in soda.
Joe is unconvinced. He remembers observing that the saucepan lid became covered in water drops as the water continued to boil.
5 How could he use this observation to convince Brian that he is wrong?
…
| Level | Description | Student Responses |
|---|---|---|
| 2 |
Student provides a complete and accurate counterargument, including some kind of comparison of the two ideas. Student makes an argument that it’s state change; therefore, it can’t be a chemical change. If water is collecting on the top of the lid, then the most likely thing that is bubbling out of the liquid water is gaseous water. Brian is wrong because if it were oxygen and hydrogen, they wouldn’t collect as water on the top of the lid. If there are water drops on the pan it suggests that the oxygen and hydrogen didn’t split |
None found.
|
| 1 |
Student provides a plausible argument, but might be incomplete or not 100% accurate. Student makes an argument that it’s a state change. |
The water vapor evaporated and landed on the lid The water boils so it evaporates |
| 0 |
Student provides an incorrect counterargument or fails to answer the question. |
It is because the water has been boiling for more than 10 minutes Try the experiment again. |
