A linked case answer shows what caused an event, what it did to people and places, and how people responded, with each step leading to the next. The links are where most of the reasoning marks sit.
This lesson builds on choosing relevant facts. Once you have the facts, you connect them.
What does a chain look like?
Think of three boxes joined by arrows. The cause leads to an impact, and a response aims at either the cause or the impact. If you cannot say which one a response targets, the link is missing.
Write the chain as short sentences with reason words. You can sketch it by hand, or check the rates behind it in the statistics and distribution explorer.
Worked example
All numbers invented. Town K received 210 mm of rain in 6 hours.
Step 1, cause with a rate. 210 ÷ 6 = 35 mm per hour. The drains were designed for 25 mm per hour, so 35 − 25 = 10 mm per hour could not drain away.
Step 2, impact that follows. The surplus water filled the streets, and 1,200 of 4,000 homes flooded. 1,200 ÷ 4,000 = 0.3, so 30% of homes.
Step 3, response aimed at the cause. The council widened the main drain to carry more water. That targets the drain limit directly.
Step 4, write one chain.
“Rain fell at 35 mm per hour, above the 25 mm per hour the drains could carry, so water backed up and 30% of homes flooded. The council widened the main drain to raise the limit, which aims at the cause of the backing up.”
The paragraph has several reason links. Each response ties to a stated cause or impact.
The mistake to watch for
The usual slip is a response that does not match the problem.
Mistaken line: “The flood damaged homes, so the council built a new road.”
The road may be a good project, but the sentence gives no reason it answers flooding.
The correction is to name the target: “The council raised the riverbank near the worst-hit streets to stop water entering homes.” Now the response points at the impact.
Check yourself
1. Rain of 90 mm fell in 3 hours on a town whose drains carry 25 mm per hour. What is the rainfall rate and the excess?
Show answer
90 ÷ 3 = 30 mm per hour. Excess = 30 − 25 = 5 mm per hour.
2. Which response matches the cause “drains too small”: a shelter, a wider drain or an alert text message?
Show answer
A wider drain. A shelter and an alert respond to impacts, not to the drain limit.
3. Rewrite “Homes flooded. Residents were moved.” as one linked sentence.
Show answer
“Water entered homes along the river, so residents were moved to a school hall for shelter.” The word “so” gives the link.
Where this leads next
Linked chains are easier to compare across cases, which is the focus of when two cases are not comparable. The food-web and energy-flow explorer shows how chains work in another topic. To practise writing chains with feedback, see online one-to-one Geography tuition.