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Grade 4 · Area

Book-drive planning: check area against two side lengths

A rectangular arrangement for a book drive has 2 rows with 11 unit squares in each row. 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
Book-drive planning: check area against two side lengths. Completed rows: 0. Area covered now: 0. Full area in square units: 222 × 11 = 220 square units covered so far.
Rows are equal and disjoint. In an area investigation each tile represents one square unit; a count of square units is not a boundary length.

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.

Completed rows
0
Area covered now
0
Full area in square units
22

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 rectangular arrangement for a book drive has 2 rows with 11 unit squares in each row. Area counts the square units covering a region without gaps or overlaps. A complete row contributes the width, and multiplying by the number of rows counts the entire covering. The complete rectangle contains 22 square units; a missing row would remove exactly 11.

A relationship to keep

2 × 11 = 22 square units

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 rectangular arrangement for a book drive has 2 rows with 11 unit squares in each row. Identify what each number measures before changing a control; the worked example refers to these starting values.

  2. STEP 2

    Follow the mathematical change

    Advance the timeline one full row at a time. Compare the running count with the equal size of each completed row. Pause on an intermediate frame and compare the picture with the live readouts.

  3. STEP 3

    Explain and test the relationship

    The complete rectangle contains 22 square units; a missing row would remove exactly 11. Change one input, predict its effect, and test whether the same relationship still works.

Your turn to explain

Make a prediction. Test your reasoning.

Book-drive planning: use the original situation. A rectangular arrangement for a book drive has 2 rows with 11 unit squares in each row. What total would one additional full row produce?

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

Compare your explanation

33 square units, because 22 + 11 = 33.

Work through a full lesson

Connect the animation to a worked example and practice questions.

Grade 4 · Geometry

Recover a rectangle from area and one side

Use division for a missing dimension and then calculate perimeter.