Chalk line

A chalk line is a tool that helps people make straight lines on surfaces like walls or floors. It works kind of like this: imagine you have a box with a little string in it. You take some chalk and rub it all over the string so it gets covered in chalk powder. Then, you stretch the string out along the surface where you want to make a straight line.

Next, you pull the string really tight and hold it in place. Then, you lift the string up a little bit and let it go. When the string snaps back onto the surface, it leaves behind a straight line of chalk powder.

Now, you can use that line as a guide to make sure your work is straight. This could be helpful for things like painting a wall, laying tiles on a floor, or building a shelf. And when you're all done, you can just wipe away the chalk powder with a damp cloth. Voila!