Level (instrument)

A level instrument is like a tool that helps you measure if something is straight or not. It has a little bubble inside that moves around. You put the tool on the thing you want to measure, like a table or a picture on the wall. Then you make sure the bubble is in the middle of the little line that's inside the tool. If it is, that means the thing you're measuring is nice and straight! If it's not, you might need to adjust it so it's straight. It's like a magic eye that helps you make sure everything is just right!