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WSP Scale Factor

  • Scale Factor

    Grade: 6th to 8th, High School

    A common misconception is that when the dimensions of an object are doubled, the area is doubled, too. But this is not true! Use this applet to investigate how changes in the scale factor influence the ratio of perimeters and the ratio of areas between two figures.

    Activity

    Instructions

    How to Use

    • Change the value of the scale factor using the rectangular window. Rectangle_B will adjust automatically adjust once you click outside the keypad or if you press Enter.
    • Dimensions are measured in pixels, since its display is universal across computers. The units cannot be altered.
    • The precision of all measurements is done to the hundredths place and cannot be altered.
    • You will not be able to drag any item around in the workspace.

    Buttons

    Any button will toggle on/off the relationship between the two measurements above it.

    Exploration

    Before using any of the buttons, explore the following:
    When the dimensions of the object are doubled, what will happen to its perimeter and area?
     

    Objectives and Standards

    NCTM Standards and Expectations
    • Geometry / Measurement
    • Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.
    • 6-8
    • High School (9-12)
    • Geometry