Box of Secrets: Understanding Variables in Code

Imagine you have a box with a label on the outside. The label says 'score'. Inside the box you can put any number you like — maybe 0 at the start of a game, then 10 after you answer a question correctly, then 25 a moment later. The box is always called 'score', but what is inside it can change. Here is a question to think about before we start: