It is important for students/consumers to understand the electrical generation mix is constantly changing as demand, weather conditions, market prices for fuels, etc, change on a daily and even hourly basis. This link is a great resource you can use to help demonstrate this fluctuation:
Integrated Marketplace Generation Mix (spp.org)
You and your students can access energy data specific to your state using this resource: U.S. Energy Information Administration - EIA - Independent Statistics and Analysis
Looking at energy from a global perspective, here is an interactive site you can have students explore to learn more:
(Be sure to have students play the time-lapse to see changes over time along with the details that can be explored by changing the options at the top of the graphics.)