A conclusion from a growth table must say what changed, by how much, and what that suggests, without claiming more than the data can show. This lesson gives you a sequence for doing that.
It is part of the SPM subjects and learning resources section. For the planning side of the subject, see explaining plant selection and layout.
How do I read a growth-observation table?
Read in this order: title, units, column headings, then values. The title tells you what was tested, the units tell you whether you are looking at centimetres or millimetres, and the headings tell you which group each column belongs to.
Then find the changed factor and the fixed factors. A fair comparison changes one thing only.
Worked example: two light conditions
This table is original. A nursery group grew chilli seedlings in two positions for four weeks. Soil, pot size and watering were the same. Heights are in centimetres.
| Seedling | Full morning sun (cm) | Under a shade net (cm) |
|---|---|---|
| 1 | 14 | 10 |
| 2 | 16 | 12 |
| 3 | 15 | 9 |
| 4 | 17 | 13 |
| 5 | 18 | 11 |
Step 1: find each average. Sun: 14 + 16 + 15 + 17 + 18 = 80, and 80 ÷ 5 = 16 cm. Shade: 10 + 12 + 9 + 13 + 11 = 55, and 55 ÷ 5 = 11 cm.
Step 2: compare. The difference is 16 − 11 = 5 cm, so the sun group averaged 5 cm taller.
Step 3: write the conclusion. “After four weeks, chilli seedlings in full morning sun averaged 16 cm, compared with 11 cm under the shade net. This suggests that these seedlings grew taller in more light, under these conditions.”
A common mistake: claiming too much
A student might write: “Sun makes all plants grow taller.” The table has one kind of seedling, five plants per group and four weeks of data.
The fix is to name the plant, the time and the conditions, and to use careful verbs such as “suggests”. A careful conclusion is not weaker. It is more accurate, and it is what a marker looks for.
Height is not the only sign of health
Height shows growth, but a nursery also watches leaf colour, stem thickness and the number of leaves. A tall seedling with thin stems and pale leaves may be stretching for light and may not be healthy.
If a table includes these columns, mention at least two measures in your conclusion. If it includes only height, say that height is the only measure given and that other signs were not recorded.
Check yourself
Using the same table, the shade net group had one more column, “leaf colour”, and four of the five seedlings were recorded as dark green while all five sun seedlings were recorded as yellow-green. Does the table still support “sun is better for chilli seedlings”? Answer in two sentences.
Answer
Not fully. Sun seedlings were taller on average, but the leaf colour record shows the shade seedlings looked greener, so “better” depends on which measure you count.
A safer conclusion is that sun gave more height while shade gave darker leaves, and more observations would be needed to decide which condition suits the seedlings overall.
What to study next
Tables are easier to interpret once you can explain why a site or plant was chosen, so revisit plant selection and layout in a landscape plan. Use the structured-answer self-review tool to check your written conclusions.
If you would like a teacher to go through your observation tables with you, see online one-to-one Landscape and Nursery tuition. Practical growing work remains with your school.