Investigating Earth — Extension · Earth & Space Science, Grade 9
Use measurements, models, maps, and reference tools to build explanations from evidence.
Build and Evaluate a Landscape Profile
Investigate
How can the same total rise hide different local slopes?
Plan three teaching sessions: define the model and comparison; run or analyze repeated supplied/collected records; then graph, explain, revise and submit the notebook. These independent home-study routes do not certify the school’s mandated investigations or laboratory minutes.
Materials
- Graph paper
- Ruler
- Pencil
- Calculator
- The supplied distance/elevation table
Before you begin
This is a paper-and-data investigation. Use supplied illustrative data or teacher-approved observations. Do not enter hazardous sites to collect evidence.
Plan a fair test
Horizontal distance is the input; elevation is the measured quantity. Keep the graph scales and distance units consistent. This observational profile is not a controlled experiment.
Method
- Predict whether equal overall gradients require identical terrain.
- Plot horizontal distance on the x-axis and elevation on the y-axis; label units.
- Connect successive observations to make a profile and calculate the gradient of each segment.
- Calculate the overall gradient from the first to last point.
- Draw a second profile with the same endpoints but different intermediate elevations.
- Explain a limitation of using only the overall gradient for route planning.
Open the investigation data (illustrative)
Illustrative data created for this activity; these are not measurements from an actual site or an official reference table.
| Distance (km) | Elevation (m) |
|---|---|
| 0 | 100 |
| 0.5 | 110 |
| 1 | 150 |
| 1.5 | 160 |
| 2 | 180 |
Analyze and explain
- Find the four segment gradients and the overall gradient.
- Which segment is steepest? Cite values.
- Why would collecting more points improve the profile?
- Identify the system boundary, units and conditions held comparable.
- Explain how the graph or figure supports the mechanism rather than merely repeat its trend.
- State one uncertainty or scale limitation and design a follow-up comparison that could challenge the explanation.
What a strong explanation includes
- Correctly scaled axes with units
- Shows each segment calculation
- Compares overall gradient with the steepest segment
- A limitation linked to sampling or averaging
- Keep observations separate from model-generated or supplied illustrative records.
- Explain a revision using the evidence and a stated model limitation.
Parent / teacher guide: discuss after the investigation
The 0.5–1 km segment rises 40 m in 0.5 km, or 80 m/km. The overall rise is 80 m in 2 km, or 40 m/km. Equal endpoint gradients can conceal different steep sections. More closely spaced observations could reveal changes between the sampled points; the profile is also only one line across the landscape. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.
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 0.5–1 km segment rises 40 m in 0.5 km, or 80 m/km. The overall rise is 80 m in 2 km, or 40 m/km. Equal endpoint gradients can conceal different steep sections. More closely spaced observations could reveal changes between the sampled points; the profile is also only one line across the landscape. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.
Problem 2
Answer and explanation
The 0.5–1 km segment rises 40 m in 0.5 km, or 80 m/km. The overall rise is 80 m in 2 km, or 40 m/km. Equal endpoint gradients can conceal different steep sections. More closely spaced observations could reveal changes between the sampled points; the profile is also only one line across the landscape. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.
Problem 3
Answer and explanation
The 0.5–1 km segment rises 40 m in 0.5 km, or 80 m/km. The overall rise is 80 m in 2 km, or 40 m/km. Equal endpoint gradients can conceal different steep sections. More closely spaced observations could reveal changes between the sampled points; the profile is also only one line across the landscape. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.
Problem 4
Answer and explanation
The 0.5–1 km segment rises 40 m in 0.5 km, or 80 m/km. The overall rise is 80 m in 2 km, or 40 m/km. Equal endpoint gradients can conceal different steep sections. More closely spaced observations could reveal changes between the sampled points; the profile is also only one line across the landscape. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.
Problem 5
Answer and explanation
The 0.5–1 km segment rises 40 m in 0.5 km, or 80 m/km. The overall rise is 80 m in 2 km, or 40 m/km. Equal endpoint gradients can conceal different steep sections. More closely spaced observations could reveal changes between the sampled points; the profile is also only one line across the landscape. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.
Problem 6
Answer and explanation
The 0.5–1 km segment rises 40 m in 0.5 km, or 80 m/km. The overall rise is 80 m in 2 km, or 40 m/km. Equal endpoint gradients can conceal different steep sections. More closely spaced observations could reveal changes between the sampled points; the profile is also only one line across the landscape. A complete notebook also specifies the boundary, measurement units and matched conditions. Describe a mechanism connecting the pattern to the claim, then state a limitation and an additional comparison. Supplied illustrative outcomes are not a claim about your collected results; differences must be interpreted rather than corrected to match the example.