Telling a Detail from the Main Idea

Step 1: Before You Read

Watch the idea first — 69 seconds. Then read on, and try it yourself in the next step.

Every detail in this article is true, and that is what makes the wrong answer tempting. Today you sort the sentences by the job they do.

Today’s story

What a Beaver Does to a River

An article, in five parts. About 230 words.

Step 2: Read the Story

One part at a time. Press Listen, or read it yourself. The tutor reads along with you.

The tutor shows

Teeth like chiselsA beaver’s front teeth never stop growing. They are orange, and they are harder on the front than on the back, so they wear into a chisel shape as the beaver gnaws. A beaver can bring down a willow as thick as your leg in a single night.

Building the damThe beaver does not eat most of the wood. It drags the branches into the stream and pushes them into a wall, packing the gaps with mud and stones until the water can no longer get through. This wall is called a dam.

What job does “they are orange” do?

The pond appearsBehind the dam, the stream stops running and spreads out. Within a few weeks there is a pond where there was once a narrow channel. The beaver builds its lodge in the middle of it, with the entrance underwater, where no fox can follow.

Who else moves inThe pond is not only for beavers. Frogs lay their eggs in the still water. Herons stand in the shallows and fish. Dragonflies hunt over the surface, and moss grows on the drowned trunks. A stretch of stream that held a handful of species now holds dozens.

And then a meadowOne day the beavers move on, and the dam breaks. The pond drains, and what is left is a flat bed of rich mud where the water stood. Grass takes it first, then flowers, then young trees. The place that was a stream, and then a pond, becomes a meadow.

Step 3: The Whole Story

Finish reading with the tutor, and the whole story appears here with its parts named.

Step 4: My Notebook

Finish the story first. Then write down two things you noticed.

Step 5: What You Learned

Details support the main idea. They answer how, why or how much.
Being true does not make a sentence the main idea.
Take away a detail and the idea survives. Take away the idea and nothing holds.

For the grown-up

Children choose the most interesting sentence as the main idea, and the most interesting sentence is almost always a detail. The reliable question is what job the sentence is doing: a detail answers how, why or how much, and the idea is what it is answering about.

Reading a page together, cover one sentence and ask whether the paragraph still makes its point. If it does, that sentence was a detail.