You read the caliper by placing an object in the caliper, closing the arm of the caliper, and reading off of the scale. In the animations you are to drag the red circle on the caliper arm to move it. ...You read the caliper by placing an object in the caliper, closing the arm of the caliper, and reading off of the scale. In the animations you are to drag the red circle on the caliper arm to move it. To figure out the hundredths place, you look to find which line on the movable arm matches up with a line on the fixed scale. Use the mouse to drag the rear bumper of the toy monster truck (the red ball).