Adult Ed

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In science, diagrams usually show the parts of something, like an electric circuit or the steps in a process, like the life cycle of a frog. In addition to providing the "big picture," diagrams provide many details as well. This diagram shows how muscles work in pairs to move the forearm.

muscle diagram

When you read a science diagram, look at these parts first to get an idea of what is being shown.
Then study the details.

  • Title or caption. Most GED science diagrams have a title that tells the topic and possibly the main idea; a few have captions. The main idea of this diagram is that muscles work in pairs to move a bone.
  • Labels. Labels are words that describe a part of the diagram. They point to the part being described. In this diagram, the labels point to the two upper arm muscles and explain what they do.

Now, study the diagram and answer this question: Which muscle contracts to bend the arm at the elbow?

First look at the part of the diagram that shows the arm bent. Then read the label to find which muscle is contracting. The label says that the biceps is contracting.


This question involves an analysis of a cause/effect relationship.

The muscles work in pairs to bend the arm because as the biceps contracts, the
  1. triceps contracts.
  2. triceps relax.
  3. shortened biceps alone pulls the forearm.
  4. triceps pulls the shoulder.
  5. triceps pulls the forearm.