Greg found CK-12 Foundation:

• Moderately improves attainment
• Significantly builds student knowledge
• Significantly improves teaching efficiency and productivity“I can look at the assignments before my student completes them and keep up in my copy of the book just like regular books but I can have them on any device anytime.”
• Significantly reduces teacher workload“I just let my student go through the work and check after.”
• Moderately saves school money“I use it for History and Science and it's free. I would be paying for those in another program. The books are free and very well done.”