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Activity (Hands-On)Grades 3 - 4

On-Track Unit Conversion

Two photos and a drawing: Six students sit on the floor working with a small robot and three tape-marked tracks. A view of a shoe-box sized robot on a linoleum floor near three long stretches of masking tape each marked with different units. A drawing of three foot-long rulers placed end-to-end with labels noting an inch, a foot and a yard. At the The Brooklyn Brownstone School.Students gain comfort in converting between distances measured in inches, feet and yards.

Students use three tracks marked on the floor, one in yards, one in feet and one in inches. As they start and stop a robot specific distances on a "runway," they can easily determine the equivalent measurements in other units by looking at the nearby tracks. With this visual and physical representation of the magnitude of the units of feet, yard and inches, students gain an understanding of what is meant by "unit conversion." They also gain a familiarity with different common units of measurement. They use multiplication and division to verify their physical estimated unit conversions. Students also learn about how common and helpful it is to convert from one unit to another in everyday situations and for engineering purposes. This activity helps students make the abstract concept of unit conversion real so they develop mental models of the magnitude of units instead of applying memorized conversion factors by rote.

Making measurements and unit conversions plays a significant role in nearly all engineering and science endeavors, as well as ordinary day-to-day situations. Almost all of the data collected by scientists and engineers have units, and these numbers are converted to other units, depending on how they are to be used in equations and calculations. Engineers identify units in all their design documentation, and must be able to convert between units to make the measurements or specifications suitable for the units being used in the projects or locations where the designs are to be implemented.

After this activity, students should be able to:

  • List different units of length.
  • Describe different lengths using physical examples.
  • Convert one unit of length into another.
  • Explain how units, measurements and conversion are used in engineering.

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