A good reflection on a small investigation states what was measured, summarises the data with a number, says what the data supports, admits what it cannot show, and proposes a better next test.
This lesson is part of SPM subjects and learning resources. It pairs with explaining an environmental design trade-off, since both rely on stated evidence.
What does the reflection need to say?
Write five short parts: question, data, what it supports, what it cannot show, and next step. Keep each to one or two sentences and put a number or detail in every part.
Worked example: a five-day bin count
An original investigation. A class counts pieces of paper thrown in the classroom bin each school day, to see whether a “use both sides” reminder on Tuesday changes waste. Counts: Monday 12, Tuesday 15, Wednesday 9, Thursday 14, Friday 10.
Question. Does the number of paper pieces thrown away change over a school week?
Data. Total = 12 + 15 + 9 + 14 + 10 = 60 pieces. Mean = 60 ÷ 5 = 12 pieces per day. The highest day was Tuesday (15) and the lowest was Wednesday (9).
What it supports. The count fell from 15 on Tuesday to 9 on Wednesday, the day after the reminder.
What it cannot show. One week in one class, with no week before the reminder to compare. Thursday went back up to 14, so the reminder may not have lasted. Wednesday’s lower count may also have been because fewer worksheets were given.
Next step. Count for a week without the reminder, then a week with it, and record the number of worksheets handed out each day.
Overclaiming and careful reflection
| Version | Text | Problem or strength |
|---|---|---|
| Overclaiming | “The reminder reduced paper waste, so the whole school should copy it.” | One class, one week, no baseline. Cause and school-wide rule are not supported. |
| Careful | “The count fell from 15 to 9 the day after the reminder, then rose to 14. One class for one week cannot show that the reminder caused the change.” | States the numbers, the pattern and the limit. |
The mistake to avoid
A common slip is treating the mean as the whole story. A mean of 12 does not show that Tuesday and Wednesday differed by 6.
Always look at the individual values next to the summary, and name any day that stands out.
Check yourself
An original investigation counts plastic bottles in a recycling box over four days: 8, 11, 7, 10. Find the mean and write two sentences that state what the data supports and one limit.
Answer
Total = 8 + 11 + 7 + 10 = 36, so the mean is 36 ÷ 4 = 9 bottles per day.
A sample: “The box held between 7 and 11 bottles a day, with a mean of 9. Four days in one class cannot show a weekly pattern, and the count does not show whether the bottles were recycled or only collected.”
The limits can differ. Check that each claim uses the numbers and does not go beyond four days.
What to study next
Practise the whole set of skills in the original Sustainability practice set, and use the structured-answer self-review tool to test your written reflection. If your comparisons still need work, go back to comparing design choices with explicit criteria.
Assessed investigations follow your school’s instructions. For help with wording and reasoning, see online one-to-one Sustainability tuition.