Safety and evidence boundary
Use the course safety charter. This instructional studio uses supplied or invented numerical examples, paper tasks, and simulations. Do not culture microorganisms or substitute unsupervised laboratory materials. Model data are not experimental findings.
Explicit science instruction
The mean is the sum of measurements divided by the number of observations. The range equals maximum minus minimum. Percent change is (new minus old) divided by the magnitude of the original value, times 100 when the original is nonzero. Always include units on measured values and identify the denominator for percentages. Neither a higher mean nor a small range by itself proves that a treatment caused the difference.
Vocabulary: mean; range; percent change; baseline; outlier.
Worked example with reasoning
Illustrative simulated measurements of leaf length (mm): Group A = 9, 10, 11; Group B = 12, 11, 13. Mean A = (9+10+11)/3 = 10 mm. Mean B = (12+11+13)/3 = 12 mm. Both ranges equal 2 mm. Relative to Group A, percent change = (12−10)/10×100 = 20%. These values describe groups, not cause. Even identical ranges do not show equal overall distributions.
Guided question
Calculate the sum before dividing. Why is 10 mm, rather than 12 mm, the denominator for the reported change from A to B?
Independent work
- Recompute both means and ranges, showing the three measured values in each group.
- If another B measurement is 20 mm, calculate the new B mean and discuss what a possible outlier does.
- Write two accurate result statements and one causal statement the data do not justify.
Misconception check
Percent increase is not found by subtracting the two numbers and appending a percent sign.
Formative understanding check
For a change from 10 mm to 12 mm, is percent change 2%, 20%, or 120%?
Show the worked response
20%; the increase is 2 mm, and 2/10 × 100 = 20%.
Self-check only; not an official mastery attempt or grade.
Mentor evidence conference
Ask Archaemenes to check your arithmetic, baseline choice, units, graph interpretation, and whether the numerical result is being overclaimed.
Archaemenes may question your reasoning and help you plan a correction, but does not determine mastery or provide protected assessment answers.
Open Archaemenes for this lessonTeacher guidance
Use synthetic data; no wet lab or culturing. Have students identify baseline and units before entering numbers in a calculator.
Foundation: calculate mean and range from scaffolded values. Core: calculate mean, range, percent change, and interpret a graph with units. Extended: compare sensitivity to an outlier and explain how uncertainty changes the claim.
Preserve learning evidence
Record calculations, model revisions, CER writing, and a correction in the original wednesday evidence field. The course's existing records and progression rules remain in control.
Return to wednesday Evidence Workspace