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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 12 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 Accidental Photograph

In 1895 Wilhelm Röntgen was working with a covered tube in a darkened room when he noticed a screen across the laboratory glowing. Something was passing through the cover and crossing the room. He did not know what it was, so he called it X — the unknown. He spent seven weeks alone in the laboratory testing it. He put wood, rubber and metal in the way. Metal stopped it; the rest did not. Then he asked his wife to put her hand between the tube and a photographic plate. The picture showed the bones of her hand and her wedding ring. Within a year, X-rays were being used in hospitals. Röntgen refused to patent them.

  1. 1. Explain the relationship between the seven weeks of testing and the photograph of the hand.
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.

LessonPrint · RI.4.3 · Set 12 · free to copy for classroom use

Answer key — What Happened and Why

Set 12. Prints on its own sheet.

  1. 1.1. The testing established that metal stopped the rays and other materials did not, which is what made the bone photograph possible.
  2. 2.1. They read the paper ten years later and took on the problem Fleming had not solved: producing penicillin in quantity.

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.