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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 6 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.

The Wolves and the Rivers

Wolves were shot out of Yellowstone by 1926. Fourteen were brought back in 1995. With no wolves, elk had grazed the valleys freely for seventy years. Young willow and aspen were eaten as soon as they grew. The wolves killed some elk. More importantly, they changed where elk would stand still. Open valley floors became dangerous, so the elk stopped lingering there. Willow and aspen grew back along the rivers. Beavers, which need willow, returned. Their dams made ponds. Roots held the banks. The rivers narrowed, deepened and moved less. Some researchers describe this as wolves changing the shape of rivers, though others argue the effect has been overstated.

  1. 1. Explain the relationship between the wolves and the shape of the rivers.
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 6 · free to copy for classroom use

Answer key — What Happened and Why

Set 6. Prints on its own sheet.

  1. 1.1. Wolves made valley floors dangerous, so elk moved on, willow grew, beavers returned and dammed, and roots held the banks.
  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.