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Grade 1 · Measurement

Reading-corner books: align ends to compare lengths

A design for a reading corner uses strips of lengths 7 and 11 equal units. Change the controls and explain what the animation reveals.

Predict what will happen, press Play, then pause and explain what changed. Every control also works without playback.

Watch the relationship

Paused
Reading-corner books: align ends to compare lengths. First amount: 7. Second amount: 11. Difference: 47 < 11 · difference 4First: 7Second: 11Compare on the same scale and from the same start.
Both strips use the same length unit and begin at the same origin. Thickness is decorative and does not represent another measured dimension.

Starts paused. Play once, pause anywhere, or use Step to inspect the mathematics. Playback stops when this panel leaves the screen.

Make it your experiment

Change one value. Notice what follows.

The controls adjust the model. Numbers below describe the current frame. Decimals are rounded.

First amount
7
Second amount
11
Difference
4

HD animation studio

From experiment to screen.

Present a crisp Canvas scene, save a full-HD image, or capture your model as a silent video.

Understand what you are seeing

The idea behind the motion.

A design for a reading corner uses strips of lengths 7 and 11 equal units. Length comparisons require a common unit and aligned starting endpoints. A longer drawing caused only by a different display scale would not be a valid comparison. The longer strip reaches 11 units from the start; the shorter reaches 7 units.

A relationship to keep

Length difference = |7 − 11| = 4

Read the symbols alongside the explanation. A diagram shows the relationship; the assumptions tell you when it applies.

  1. STEP 1

    Read the starting situation

    A design for a reading corner uses strips of lengths 7 and 11 equal units. Identify what each number measures before changing a control; the worked example refers to these starting values.

  2. STEP 2

    Follow the mathematical change

    Trace both strips from their shared starting line. Compare the endpoints after both complete lengths are visible. Pause on an intermediate frame and compare the picture with the live readouts.

  3. STEP 3

    Explain and test the relationship

    The longer strip reaches 11 units from the start; the shorter reaches 7 units. Change one input, predict its effect, and test whether the same relationship still works.

Your turn to explain

Make a prediction. Test your reasoning.

Reading-corner books: use the original situation. A design for a reading corner uses strips of lengths 7 and 11 equal units. What extension would make the shorter strip exactly as long as the longer one?

Use the values specified in the question. Reset restores the initial values for this investigation.

Compare your explanation

4 units, because 7 + 4 = 11.

Work through a full lesson

Connect the animation to a worked example and practice questions.

Grade 1 · Geometry

Order objects by length

Compare lengths by aligning one endpoint.