This one is pretty math oriented (no, really?). Simply put, you have to know about math before you can teach it to someone. Math teachers typically use lots of different math skills because of the nature of the job.
A lot of scientists use math on a daily basis. The type of math depends on what they study (botanists and zoologists use statistics to keep track of animal populations, physics people use formulas and equations that have to do with speed, distance, velocity, etc, rocket scientists use math to help build and fly their rockets...).