Which sustainability metric has had the biggest impact on how mathematics textbooks and manipulatives are manufactured and distributed in the last decade?

The mathematics education sector has been evolving to incorporate sustainability principles in how educational products are designed, manufactured, and distributed. From carbon footprint calculations of textbooks to the environmental impact of digital learning tools, mathematics retailers are finding innovative ways to quantify and reduce their environmental impact. Test your knowledge about how the mathematics education retail sector is embracing sustainability!

This is a live public trivia poll on AIPolls.Net. Vote and see real-time results.

Carbon footprint calculation of paper production vs. digital distribution (measured in CO₂ equivalent per student learning hour)
Water usage reduction in manufacturing manipulatives (measured in gallons saved per product unit)
Plastic reduction index for packaging math manipulatives (measured in percentage of recycled materials)
Energy efficiency ratio of mathematical software development (measured in kilowatt-hours per software update)