Tools for math education
If you want to be a great math educator, I recommend learning all of the following tools:
Beamer - You can make presentations easily in LaTeX using this software!
Geogebra - You can make interactives to help your students understand geometry theorems.
Isabelle - Students can experiment with natural deduction proofs using this software. It's especially helpful for gaining a mechanical understanding of proofs.
Desmos - You can create interactives so students can explore graph transformations. By using the API you can quickly generate images for your presentations too. Students can also visualize solutions to linear equations, absolute value equations, roots of quadratics, etc.
SageMath - Useful for checking answers to most arithmetic and algebra homework problems.
LaTeX - You can use this to typeset math problems.
tkzeuclide - A LaTeX package that helps you make diagrams for teaching high school geometry.