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What Happened and Why is a free printable Grade 4 English worksheet on explaining an event using the text's own information, aligned to Common Core standard RI.4.3. It prints 2 questions with an answer key on its own sheet of paper, in 25 versions, 19 of them with 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 13 of 25 · the same problems every time you open this link.

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Set 1 has all 25 in a single PDF. 19 of these 25 sets ask different questions — this skill does not have 25 questions to give. The rest reorder them, so no two pupils have the same paper in front of them.

What Happened and Why

RI.4.3

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. Explain the relationship between the polyp and the algae.
2.Read the text, then answer the questions.

What a Beaver Dam Does

A beaver does not build a dam for shelter. It builds one to make a pond, and it lives in a lodge in the pond. The dam raises the water so the lodge entrance stays underwater. A predator that cannot swim cannot get in. But the pond does far more than protect one family. Behind a dam, water slows, and slow water drops the silt it carries. Over years this builds rich wet ground. That ground holds water in a drought and holds it back in a flood. It supports plants, insects, amphibians and birds that were not there before. Where beavers have been reintroduced, the number of species in a valley typically rises within five years.

  1. 1. Explain the relationship between the dam and drought protection.

LessonPrint · RI.4.3 · Set 13 · free to copy for classroom use

Answer key — What Happened and Why

Set 13. Prints on its own sheet.

  1. 1.1. 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.
  2. 2.1. The dam slows water, silt builds rich wet ground, and that ground holds water through a drought.

More practice for RI.4.3

Explain what happened and why, using the text's own information.

Teaching this next? Explaining Events, Procedures and Ideas is the 40-minute plan for it, with the misconceptions to expect.

All Grade 4 worksheets

Last reviewed 2026-09-05. Aligned to RI.4.3 of the Common Core State Standards for English language arts.