Practise calculating distance, speed and time using a bar model Practise calculating distance, speed and time using bar models. You might need a pen and paper to help with your answers.

In this classic physics problem, students often make an incorrect assumption about the tension. Here's how to actually solve this.

This technique for measuring distance involves some gut-level estimation, but it's pretty easy. You just have to guess—or know—the size of an object in the distance. If you find yourself ...