Julian found mathigon--textbook-of-the-future:

• Builds student knowledge“Taught me fundamental ideas behind parts of calculus”
• Improves teaching efficiency and productivity“Very well put together textbook style learning, interactivity greatly enhances knowledge retention”
• Teach-problem-solvings
• Improves creativity and critical thinking“Interactivity”
• Improves creativity and critical thinking“Interactivity”
• Improves parent engagement“makes math more fun”