When you measure the length of a straight surface, you use a ruler or a tape measurer. These tools aren’t as useful when you need to measure the length of a curve; instead, you need a curvimeter, which is even more exact than a compass. To learn about this invention and build a model you’ll be proud to display, purchase the UGears STEM LAB Curvimeter. This item looks like a clock, except that its face displays distances in centimeters, inches, meters, and feet rather than times. To use the device, you roll the wheel across the item that needs measuring. As the wheel moves, the measuring hand moves as well, tracking how far the wheel has traveled. If your distance is greater than one rotation, the device also tracks how many circuits it has completed. Once you’ve measured the entire item, multiply the number displayed on the face by the number of rotations to find the total distance.