Not only can technology aid teachers in teaching their content in class, but technology can be used alone to give a complete lesson. This is a great thing for many reasons. Students who may be absent in class, can get the complete lesson, complete with teacher explanations. Instructional videos, or pod-casts, also allow students to review teh content as many times as they need to. This type of video can also lend itself to a flipped lesson plan, in which the lesson is given as a homework assignment to watch the podcast, and then the concept is practiced and questions can be answered in class.
Here is a link to a podcast I created about ordered pairs: https://www.dropbox.com/s/ckle4e5tcu0ob5s/Instructional%20Video.mp4?dl=0