I am trying to involve 7th grade students in economics and also improve their appreciation of math. Do you have courses for ages 12-14?

We don’t have a course specifically designed for that age but I think you could find useful content in both Everyday Economics and Principles. I have a 7 year old and he enjoys them!
Here are some ideas. Drop us a note at support@mruniversity.com if you have a specific topic in mind. If we don’t have it we might be able to suggest some other places.
Trade, Division of Labor, etc
http://www.mruniversity.com/courses/everyday-economics/trade-growth-hockey-stick-human-prosperity
Incentives
http://www.mruniversity.com/courses/principles-economics-microeconomics/introduction-microeconomics
Price signals
http://www.mruniversity.com/courses/principles-economics-microeconomics/price-system-definition-invisible-hand
Trade-off between fun and wages
http://www.mruniversity.com/courses/principles-economics-microeconomics/tradeoff-wages-no-such-thing-as-free-lunch
Public Goods
http://www.mruniversity.com/courses/principles-economics-microeconomics/public-goods-example-asteroid-defense
Basics about institutions, growth rates, development
http://www.mruniversity.com/courses/principles-economics-macroeconomics/gdp-per-capita-purchasing-power-parity-example
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