This packet is everything a parent or guide needs to assess Unit 04 at home — learning targets, the answers that count as correct, the mastery rubric, calibration examples, and a clipboard score sheet. No multiple-choice test: the student shows mastery by designing a fair test whose result no one could wave away.
By the end of the Designing a Controlled Experiment unit, a student should be able to:
Six criteria, each judged Not yet / Approaching / Mastered (Page 3).
Plan and set up a controlled experiment — watched live.
The student defends each design choice aloud (Page 4).
Design, procedure, and results kept distinct.
You are making a decision, not adding up points. For each criterion, decide whether the work is Not yet, Approaching, or Mastered — the column language tells you which. A criterion counts as mastered only when the student can both design the fair test and defend why the comparison is fair. A student carries three tokens per term; one token buys a re-do of one criterion on another day, so a single bad afternoon never sinks the unit.
Accept any answer in the synonyms column — they are pre-approved as equivalent. The third column flags the confusions that look close but are not yet, so you can coach precisely.
| Canonical answer | Accepted synonyms | Common confusion / discriminator |
|---|---|---|
| Variables & fair tests | ||
| Independent variable | what you change | The one thing changed on purpose (lamp vs. window) |
| Dependent variable | what you measure | The result you record (seedling height) |
| Controlled variable | what you hold steady | Same soil, water, pot — so one change explains a difference |
| Comparison & trust | ||
| Control group | untreated baseline | An identical setup left in ordinary conditions |
| Fair test | one thing changed at a time | Change several and no result points to a cause |
| Replication | repeating the test | Repeats guard against a fluke |
| Sample size | how many you test | Too few can’t tell a real effect from chance |
| Procedure | the written steps | Complete enough for a stranger to follow exactly |
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Independent & dependent variables | Cannot say what is being changed or what is being measured. | Names one but confuses the changed factor with the measured result. | Names the one thing changed on purpose and the one thing measured, clearly and out loud. |
| Controlled variables (fair test) | Changes several things at once, so no result could point to a cause. | Holds some factors steady but lets one or two others drift. | Holds every other factor steady so the one change is the only possible explanation. |
| Control / comparison group | Runs only the test condition with nothing to compare against. | Knows a control is needed but sets up one that isn’t truly identical. | Builds in a proper control or comparison group as a real baseline. |
| Replication & sample size | Tests one item once and treats it as proof. | Repeats the test but with too few samples to trust. | Plans enough trials and samples that a real effect can be told from a fluke. |
| Procedure clarity | Steps are vague; no one else could follow them. | Writes steps but leaves gaps a stranger would have to guess at. | Writes a procedure clear enough for another person to run it without asking a question. |
| Integration (cross-domain) | Treats experiment design as isolated; makes no connection to the anchor. | Mentions Semmelweis but cannot frame his wards as a controlled comparison. | Connects the fair test to Semmelweis’s washed-vs-unwashed wards across History · Reading · Statistics and defends why the comparison proved it. |
The split between Approaching and Mastered is could this test actually prove a cause? One thing changed, everything else held, a real baseline to compare against. Ask: how do you know it was the light and not the water?
Read these before you grade. They show what Mastered and Not yet actually sound like, plus the edge cases where you should coach rather than decide on the spot.
Student: ______________________________________ Date: _______________ Guide: _________________________
| # | Criterion | Decision | Notes |
|---|---|---|---|
| 1 | Independent & dependent variables | NY / Appr / Mast | |
| 2 | Controlled variables (fair test) | NY / Appr / Mast | |
| 3 | Control / comparison group | NY / Appr / Mast | |
| 4 | Replication & sample size | NY / Appr / Mast | |
| 5 | Procedure clarity | NY / Appr / Mast | |
| 6 | Integration (cross-domain) | NY / Appr / Mast |
☐ No ☐ Yes — for criterion: __________ Tokens remaining: ☐ 3 ☐ 2 ☐ 1 ☐ 0
NY = Not yet · Appr = Approaching · Mast = Mastered · Unsure between two levels? Circle the lower one and note what a re-do would need.