Inquiry, Measurement & Models — Extension · Science 6: Matter, Energy & Earth Systems, Grade 6
What makes a scientific explanation traceable and testable? Under one defined mass-and-draining method, which equal-sized towel sample retains more water?
Compare towel absorbency fairly
Investigate
Under one defined mass-and-draining method, which equal-sized towel sample retains more water?
Three 35–45-minute sessions: plan and predict; examine or collect evidence; explain, revise, and reflect. Use the complete supplied record when materials, time, access, or safe conditions are unavailable.
Materials
- Two clean towel materials cut by an adult into equal-sized samples, or the supplied record.
- A balance suitable for gram-scale readings, a tray, clean room-temperature tap water, and a timer.
- A notebook with trial, dry mass, wet mass, and method notes.
Before you begin
Use clean materials over a spill tray and keep water away from powered devices. A parent handles cutting and chooses a suitable measuring setup. This is an absorption comparison, not a product-safety or food test.
Plan a fair test
Change towel material. Measure wet-minus-dry mass after matched soaking and drainage. Keep sample dimensions, water source/amount, soak time, draining time, balance method, and handling comparable. Use fresh samples for each repeat.
Method
- State the absorption question and define what mass gain will measure. Predict a result with a reason.
- Prepare three equal-sized fresh samples of each material. Record dry masses and sample dimensions.
- Under the parent-approved method, soak each for the same 30 seconds and drain for the same 10 seconds without squeezing. Use enough clean water for each matched trial.
- Record wet mass promptly using the same procedure. Calculate wet minus dry for every sample, including unexpected results. If tools are unavailable, examine all six supplied rows.
- Compare individual gains, ranges, and mean gains. Check whether another changed condition could explain a difference.
- Write a claim with numerical evidence, explain the mass-gain reasoning, name a limit, and propose a better repeat. Save the earlier prediction.
Supplied illustrative record — use when an actual test is unavailable
Illustrative classroom data authored for analysis, not measurements from a real learner, stream, product, or field study. Actual observations may differ; record them honestly and compare the methods.
| Material/trial | Dry mass (g) | Wet mass (g) | Gain (g) |
|---|---|---|---|
| A / 1 | 2 | 9 | 7 |
| A / 2 | 2 | 10 | 8 |
| A / 3 | 2 | 8 | 6 |
| B / 1 | 2 | 6 | 4 |
| B / 2 | 2 | 7 | 5 |
| B / 3 | 2 | 8 | 6 |
Analyze and explain
- Calculate each material’s mean gain and range. How do the results compare?
- Why are matched draining time and sample dimensions important?
- Which claim is supported, and which meanings of best remain untested?
- How would you investigate whether the difference persists?
What a strong explanation includes
- A defined question and measured response.
- Correct mass gains, means, units, and range.
- Reasoning linking water retention with mass change.
- Controlled conditions and an honest limit.
- A proposed repeat or improvement supported by the method.
Parent / teacher guide: discuss after the investigation
The supplied A gains are 7, 8, and 6 g, with mean 7 g and range 6–8 g. B gains are 4, 5, and 6 g, with mean 5 g and range 4–6 g. The mean difference is 2 g under the stated method. Water retained adds mass, so these comparable gains support greater retained water in A for this absorption procedure. The overlap at 6 g is a reminder that the records vary; it does not erase the mean difference or guarantee every future A sample beats every B sample. The conclusion depends on consistent dimensions, soaking, drainage, and weighing. Squeezing only one material or leaving one to drain longer would change the measured outcome. A higher gain from a much larger piece would also fail to isolate material. Repeated fresh samples help describe variation; selecting only A’s highest trial and B’s lowest would exaggerate the evidence. A defensible statement is that A retained more water on average in this illustrative comparison, not that it is universally the best towel. Cost, reuse, waste, strength, and other spills were not measured. A next investigation could use more fresh pieces with the same method or test one specified different draining time while keeping other conditions comparable. If actual results differ, inspect the procedure and explain them rather than replace them with the supplied numbers.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.
Extend the chapter investigation by evaluating its evidence and proposing a better test.
Problem 1
Answer and explanation
The supplied A gains are 7, 8, and 6 g, with mean 7 g and range 6–8 g. B gains are 4, 5, and 6 g, with mean 5 g and range 4–6 g. The mean difference is 2 g under the stated method. Water retained adds mass, so these comparable gains support greater retained water in A for this absorption procedure. The overlap at 6 g is a reminder that the records vary; it does not erase the mean difference or guarantee every future A sample beats every B sample. The conclusion depends on consistent dimensions, soaking, drainage, and weighing. Squeezing only one material or leaving one to drain longer would change the measured outcome. A higher gain from a much larger piece would also fail to isolate material. Repeated fresh samples help describe variation; selecting only A’s highest trial and B’s lowest would exaggerate the evidence. A defensible statement is that A retained more water on average in this illustrative comparison, not that it is universally the best towel. Cost, reuse, waste, strength, and other spills were not measured. A next investigation could use more fresh pieces with the same method or test one specified different draining time while keeping other conditions comparable. If actual results differ, inspect the procedure and explain them rather than replace them with the supplied numbers.
Problem 2
Answer and explanation
The supplied A gains are 7, 8, and 6 g, with mean 7 g and range 6–8 g. B gains are 4, 5, and 6 g, with mean 5 g and range 4–6 g. The mean difference is 2 g under the stated method. Water retained adds mass, so these comparable gains support greater retained water in A for this absorption procedure. The overlap at 6 g is a reminder that the records vary; it does not erase the mean difference or guarantee every future A sample beats every B sample. The conclusion depends on consistent dimensions, soaking, drainage, and weighing. Squeezing only one material or leaving one to drain longer would change the measured outcome. A higher gain from a much larger piece would also fail to isolate material. Repeated fresh samples help describe variation; selecting only A’s highest trial and B’s lowest would exaggerate the evidence. A defensible statement is that A retained more water on average in this illustrative comparison, not that it is universally the best towel. Cost, reuse, waste, strength, and other spills were not measured. A next investigation could use more fresh pieces with the same method or test one specified different draining time while keeping other conditions comparable. If actual results differ, inspect the procedure and explain them rather than replace them with the supplied numbers.
Problem 3
Answer and explanation
The supplied A gains are 7, 8, and 6 g, with mean 7 g and range 6–8 g. B gains are 4, 5, and 6 g, with mean 5 g and range 4–6 g. The mean difference is 2 g under the stated method. Water retained adds mass, so these comparable gains support greater retained water in A for this absorption procedure. The overlap at 6 g is a reminder that the records vary; it does not erase the mean difference or guarantee every future A sample beats every B sample. The conclusion depends on consistent dimensions, soaking, drainage, and weighing. Squeezing only one material or leaving one to drain longer would change the measured outcome. A higher gain from a much larger piece would also fail to isolate material. Repeated fresh samples help describe variation; selecting only A’s highest trial and B’s lowest would exaggerate the evidence. A defensible statement is that A retained more water on average in this illustrative comparison, not that it is universally the best towel. Cost, reuse, waste, strength, and other spills were not measured. A next investigation could use more fresh pieces with the same method or test one specified different draining time while keeping other conditions comparable. If actual results differ, inspect the procedure and explain them rather than replace them with the supplied numbers.
Problem 4
Answer and explanation
The supplied A gains are 7, 8, and 6 g, with mean 7 g and range 6–8 g. B gains are 4, 5, and 6 g, with mean 5 g and range 4–6 g. The mean difference is 2 g under the stated method. Water retained adds mass, so these comparable gains support greater retained water in A for this absorption procedure. The overlap at 6 g is a reminder that the records vary; it does not erase the mean difference or guarantee every future A sample beats every B sample. The conclusion depends on consistent dimensions, soaking, drainage, and weighing. Squeezing only one material or leaving one to drain longer would change the measured outcome. A higher gain from a much larger piece would also fail to isolate material. Repeated fresh samples help describe variation; selecting only A’s highest trial and B’s lowest would exaggerate the evidence. A defensible statement is that A retained more water on average in this illustrative comparison, not that it is universally the best towel. Cost, reuse, waste, strength, and other spills were not measured. A next investigation could use more fresh pieces with the same method or test one specified different draining time while keeping other conditions comparable. If actual results differ, inspect the procedure and explain them rather than replace them with the supplied numbers.