Main Idea and Its Support is a free printable Grade 4 English worksheet on stating a main idea and how the details hold it up, aligned to Common Core standard RI.4.2. It prints 2 questions with an answer key on its own sheet of paper, in 25 versions, 21 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 1 of 25 · the same problems every time you open this link.
21 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.
Main Idea and Its Support
RI.4.2
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. Determine the main idea of this text and explain how key details support it.
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. Determine the main idea of this text and explain how key details support it.
LessonPrint · RI.4.2 · Set 1 · free to copy for classroom use
Answer key — Main Idea and Its Support
Set 1. Prints on its own sheet.
1.1. An accidental observation became a medical tool within a year — supported by the seven weeks of testing and the hospital use.
2.1. Discovering penicillin was only the start — the details about Florey, Chain and two thousand litres show that making it usable was the real work.
Questions about Main Idea and Its Support
What does the Main Idea and Its Support worksheet cover?
It practises stating a main idea and how the details hold it up — 2 questions for Grade 4, all on Common Core RI.4.2: State the main idea, show the details behind it, and summarise. The instruction to pupils is “Read the text, then answer the questions”, and the answer key follows on the next sheet.
Which Common Core standard does Main Idea and Its Support practise?
CCSS.ELA-LITERACY.RI.4.2 — RI.4.2, in the Reading: Informational Text domain for Grade 4. The published standard reads: “Determine the main idea of a text and explain how it is supported by key details; summarize the text.” The worksheet assesses that standard rather than a paraphrase of it.
What age or grade is this worksheet for?
Main Idea and Its Support is written for Grade 4, typically ages 9-10. It is one of the sheets on RI.4.2, so it suits any pupil working at that standard — including older pupils revisiting it and younger ones working ahead.
Does Main Idea and Its Support come with an answer key?
Yes. All 2 answers are generated from the same problems as the questions, so the key cannot drift out of step with the sheet. It starts on a fresh sheet of paper, after the questions, so it is not handed out with the class by accident.
How many different versions of Main Idea and Its Support can I print?
25 versions, of which 21 ask genuinely different questions — this skill does not have 25 distinct questions to give, so the rest reorder them and no two pupils still share a paper. Set 1 downloads all 25 as one PDF.
Is Main Idea and Its Support free to print and photocopy?
Yes. Main Idea and Its Support, its answer key and its 25 versions are free to print and photocopy for your own class, with no account, no email capture and no subscription at the download step. Please do not resell them or republish them as your own.
Is there a lesson plan to teach RI.4.2?
Yes — “The Main Idea and a Summary” is a 40-minute Grade 4 plan for RI.4.2, timed section by section, with the misconceptions to expect and an exit ticket. Main Idea and Its Support is the practice that follows it.
More practice for RI.4.2
State the main idea, show the details behind it, and summarise.
Teaching this next? The Main Idea and a Summary is the 40-minute plan for it, with the misconceptions to expect.