Explain a seed-growth comparison

1. Plan before collecting

Choose a teacher-reviewed, low-risk seed-growing comparison or an appropriately licensed longitudinal dataset. For a physical study, use ordinary planting materials and follow their instructions; do not eat study plants, add experimental chemicals or handle moldy material. Arrange adult or instructor review for setup and disposal. An observation-only dataset pathway remains available.

For example, investigate a modest difference in daily light exposure while holding the planting medium, seed source and watering procedure constant. Use separate containers assigned to groups where possible, and record location. If one tray receives each condition, plants within a tray are not independent treatment replicates. Additional measurements of the same plant are repeated observations, not additional plants.

Predeclare day 0, a final day from 1–60, and at least one intermediate observation. Measure from a consistent landmark, such as soil surface to the growing shoot tip, in millimeters. A plant not yet emerged may have height zero under that definition; an unmeasured plant is missing. Germination success is a separate outcome. Retain failed, unusual and missing cases rather than silently excluding them.

This label records your declaration. It does not authenticate measurements or establish practical competence.

2. Record repeated observations

Use the exact header below, followed by one row per plant and day. Plant IDs use letters, digits, hyphens or underscores; groups are A or B. Keep each plant in its assigned group. Heights range from 0–1000 mm; leave the height field empty for a missing observation. Limits: 24 plants and 120 rows. No quoted fields or spreadsheet formulas are accepted.

plant,group,day,height_mm
a1,A,0,3
a1,A,3,8
a1,A,7,

The example is invented format guidance, not a dataset or a complete investigation. Do not report it as measured evidence. Changes in the observation editor are unsaved until you select “Save observations.”

3. Compare within-plant changes

For each plant with both endpoints, change = height on day 7 minus height on day 0. The group mean averages those changes, not every row. Negative changes are retained. Intermediate observations support interpretation but are not counted as independent replicates. Missing endpoints are excluded from this paired calculation and counted explicitly; that exclusion can bias the result.

Group A

0 plants recorded; 0 complete endpoint pairs; 0 plants without a complete pair. Mean change: unavailable.

Group B

0 plants recorded; 0 complete endpoint pairs; 0 plants without a complete pair. Mean change: unavailable.

Inspect individual changes before trusting the mean. Explain whether an apparent difference is driven by one plant, whether initial sizes differ, and whether losses are concentrated in one group. Do not invent measurements to fill gaps.

4. Defend and submit

A submission requires all six report fields and at least two plants with day 0, an intermediate observation and the selected endpoint in each group. This minimum checks report structure, not adequate sample size or independent experimental replication. The reviewer evaluates the design and evidence.

The first report is retained permanently in this local workflow. Edit the draft after critique, then save one revised report. Legacy submitted reports become the retained first report; none are silently replaced.

Review rubric

For each criterion, a reviewer should record “supported,” “needs revision,” or “not evidenced,” cite the relevant observation or passage, and suggest a targeted retry.

1. Question, mechanism and prediction were explicit before results were interpreted.
2. Assignment, controls, independent units, measurement landmarks and uncertainty are reconstructable.
3. Provenance and the measured/practice distinction are honest and traceable.
4. Repeated observations, missingness, individual variation and paired arithmetic are represented accurately.
5. The conclusion addresses alternative explanations and the limits of causal inference.
6. A new case or follow-up design could challenge the claim; the learner explains what result would change their view.

Transfer prompt: both groups have the same final mean height, but group B began taller. Explain why final height alone and within-plant change answer different questions. Then propose how you would handle unequal starting heights in a new study.