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Following a Chain of Causes is a free printable Grade 4 English worksheet on holding a multi-step causal chain together, aligned to Common Core standard RI.4.10. It prints 2 questions with an answer key on its own sheet of paper, in 25 versions that each ask different questions, so no two pupils in the class work from the same page. Print it from the browser or download it as a PDF — no account, no email.

Set 7 of 25 · the same problems every time you open this link.

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Set 1 has all 25 in a single PDF. All 25 sets ask different questions.

Following a Chain of Causes

RI.4.10

NameDate

Read the text, then answer the questions.

1.Read the text, then answer the questions.

What a Coral Reef Is

A coral reef looks like rock and is built by animals. A coral polyp is a soft creature the size of a pinhead. It draws calcium from the sea water and builds a hard cup around itself. Millions of polyps, cup upon cup, become a reef. Inside each polyp live tiny algae. The algae make food from sunlight and pass most of it to the polyp. In exchange they get shelter and the polyp's waste. Neither could build a reef alone. When the water gets too warm, the polyps expel the algae. Without them the coral turns white and starves. That is what bleaching means. A reef takes centuries to build and can bleach in a single hot summer.

  1. 1. Put these in order: the coral turns white, the water warms, the polyps expel the algae.
  2. 2. Explain the relationship between the polyp and the algae.
  3. 3. Summarise this text.
2.Read the text, then answer the questions.

How Penicillin Was Found

In 1928 Alexander Fleming went on holiday and left a stack of dishes on a bench. Each held a colony of bacteria. When he came back, one dish had a spot of mould on it. Around the mould was a clear ring where the bacteria had died. Fleming realised the mould was producing something that killed bacteria. He named it penicillin and published a paper. Almost nobody noticed. Ten years later, Howard Florey and Ernst Chain read that paper and tried to make penicillin in quantity. That turned out to be the hard part: it took two thousand litres of mould fluid to treat one patient. By 1944 the problem had been solved and penicillin was reaching soldiers in the field.

  1. 1. Explain the relationship between Fleming's paper and Florey and Chain's work.
  2. 2. Summarise this text.
  3. 3. Put these in order: penicillin reaches soldiers, Fleming publishes, Florey and Chain read the paper.

LessonPrint · RI.4.10 · Set 7 · free to copy for classroom use

Answer key — Following a Chain of Causes

Set 7. Prints on its own sheet.

  1. 1.1. The water warms, the polyps expel the algae, the coral turns white. 2. The algae make food from sunlight and give most of it to the polyp; the polyp gives them shelter and its waste. Neither builds a reef alone. 3. Coral reefs are built by pinhead-sized polyps that make calcium cups and live in partnership with algae, and warm water breaks that partnership and bleaches the reef.
  2. 2.1. They read the paper ten years later and took on the problem Fleming had not solved: producing penicillin in quantity. 2. Fleming spotted mould killing bacteria in 1928 and published to no response; Florey and Chain solved the production problem, and by 1944 penicillin reached soldiers. 3. Fleming publishes, Florey and Chain read the paper, penicillin reaches soldiers.

Last reviewed 2026-09-05. Aligned to RI.4.10 of the Common Core State Standards for English language arts.