THSB
Substances, Chemical Reactions, and Conservation of Matter
Whenever substances within a closed system interact with one another, the total mass of the system remains the s…
Item SC075004: When mold grows on a piece of bread in a sealed container, the bag and its contents weigh the same before and after the mold start growing.
A student placed a piece of bread in a plastic bag. He sealed the bag so that nothing could get in or get out. After two weeks, he noticed mold growing on the bread. (Note that the mold’s weight increases as it grows.)
The student weighed the bag and its contents before and after the mold started growing. After two weeks, did the bag and its contents weigh the same, more, or less than it did before the mold started growing?
- The bag and its contents weighed the same.
- The bag and its contents weighed more.
- The bag and its contents weighed less.
- More information is needed to tell if the weight of the bag and its contents changed.
Explain why you selected the answer choice you did. Be as complete as you can and include science ideas in your explanation.*
Pre-Test
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 376 |
6–8 n = 376 |
9–12 n = 0 |
Male n = 206 |
Female n = 170 |
English n = 348 |
Other n = 28 |
||
| A. | The bag and its contents weighed the same. | 18% | 18% | NAN% | 21% | 14% | 19% | 4% |
| B. | The bag and its contents weighed more. | 66% | 66% | NAN% | 60% | 73% | 65% | 71% |
| C. | The bag and its contents weighed less. | 7% | 7% | NAN% | 9% | 5% | 7% | 7% |
| D. | More information is needed to tell if the weight of the bag and its contents changed. | 10% | 10% | NAN% | 10% | 9% | 9% | 18% |
Post-Test
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 378 |
6–8 n = 378 |
9–12 n = 0 |
Male n = 207 |
Female n = 171 |
English n = 350 |
Other n = 28 |
||
| A. | The bag and its contents weighed the same. | 57% | 57% | NAN% | 64% | 50% | 60% | 29% |
| B. | The bag and its contents weighed more. | 36% | 36% | NAN% | 29% | 44% | 36% | 39% |
| C. | The bag and its contents weighed less. | 4% | 4% | NAN% | 4% | 4% | 3% | 21% |
| D. | More information is needed to tell if the weight of the bag and its contents changed. | 3% | 3% | NAN% | 3% | 2% | 2% | 11% |