Let's say that you wanted to know the approximate presssure of a gas for a temperature that was beyond the range of the thermometer; EXTRAPOLATION is the name given to the method that you'll need to use.

• Take a ruler and line it up with the line you graphed.

• Extend the line as far to the left as you want.

• Do the same thing to the right hand side of the line.

• We call this "extrapolation," and it's a neat way to make more sense out of your data and your graph.