A claim is supported when its wording is no stronger than the evidence. Look for absolute words, quote the data behind the claim, and say what the data covers.
This lesson completes environmental sustainability. It needs the same care as separating association from a demonstrated cause.
What is the word-strength ladder?
| Strength | Phrase | Use when |
|---|---|---|
| Strongest | proves, always, is the cause | A controlled test with repeats supports it |
| Middle | shows, leads to | The data clearly supports it in this case |
| Careful | suggests, is associated with | A survey shows a pattern only |
| Weakest | may be related to | Few data points or other factors possible |
Pick the rung that matches the evidence, not the one that sounds best.
Worked example: three overclaims rewritten
The data in each case is invented.
Claim 1. “Plastic waste kills all the fish in the river.” Dead fish were recorded at one site only. Better: “Dead fish were found at one site near plastic waste, which suggests a possible link, but the cause of death was not tested.”
Claim 2. “The project proves the forest is recovering.” Tree counts rose from 120 to 150 over two years. Better: “Tree counts rose by 25% over two years, which suggests early recovery, but a longer record is needed.”
Claim 3. “Fertiliser is the only reason fish are declining.” Better: “Fertiliser runoff may contribute to the decline, but temperature and fishing were not measured, so other factors cannot be ruled out.”
Check claim 2: (150 − 120) ÷ 120 × 100 = 25%.
The mistake that costs marks
The common error is to write a bold sentence first and look for data afterwards. Do it the other way round: read the data, name what it covers, then choose the wording.
A second error is to drop the scope. “The river” and “one site on the river” are different claims.
How do you add support?
Give a figure, name its scope, and add one line on what would strengthen it: “More sites and several years of data would give stronger support.”
Check yourself
The data shows that a bird count rose from 30 to 36 in one reserve in one year. A student writes “the conservation plan has saved the birds.” Rewrite it.
Answer
“The bird count rose from 30 to 36, an increase of 20%, in one reserve over one year. This suggests the plan may be helping, but one year and one reserve are not enough to be sure.”
The check: (36 − 30) ÷ 30 × 100 = 20%.
What to study next
Test all four skills in the practice set. The biological data interpretation trainer has more claims to check, and the mistake log is where you can note your overclaims.
If you want a teacher to tighten your written conclusions with you, see online one-to-one Biology tuition.