Qualitative and quantitative observations — Apply worksheet
Original practice. Write explanations that distinguish observations, evidence and claims.
Name: __________________________ Date: ______________
Read a rock-column record
Text description
- Depth increases downward from the top of the exposed column. Layer A, pale and fine-grained, extends from 0 to 0.4 m. Layer B, dark and coarse-grained, extends from 0.4 to 1.0 m. Layer C, banded and fine-grained, extends from 1.0 to 1.8 m. No faults, folds or intrusions are shown.
Depth increases downward from the top of the exposed column. Layer A, pale and fine-grained, extends from 0 to 0.4 m. Layer B, dark and coarse-grained, extends from 0.4 to 1.0 m. Layer C, banded and fine-grained, extends from 1.0 to 1.8 m. No faults, folds or intrusions are shown.
| Layer (top to bottom) | Top depth (m) | Bottom depth (m) | Description |
|---|---|---|---|
| A | 0 | 0.4 | Pale; fine grains |
| B | 0.4 | 1 | Dark; coarse grains |
| C | 1 | 1.8 | Banded; fine grains |
Question 1
Use the synthetic rock column above. Calculate the thickness of B and C and the total exposed column. Explain why layer labels are not quantitative data.
Question 2
A balance has a display increment of 0.001 g and displays 5.000 g for a 4.900 g reference. Distinguish display resolution and accuracy.
Question 3
For the synthetic rock column, give one qualitative record and one age inference. State the assumption needed for the inference and one thing thickness cannot tell you.
Teacher answer key — 3 questions
Model responses identify the essential ideas. Accept scientifically correct alternatives that address the question; wording need not match exactly.
- B = 1.0 − 0.4 = 0.6 m; C = 1.8 − 1.0 = 0.8 m; total = 1.8 m. A/B/C identify layers; they are not measured magnitudes. The boundary depths are quantitative records.
- The display increment is 0.001 g, but the reference comparison shows a +0.100 g discrepancy. A small display increment does not remove bias.
- B is dark and coarse-grained is a qualitative description. C was deposited before B and A if the layers were deposited in order and remain undisturbed. Thickness does not give an absolute age or deposition duration; further geological evidence is required.