This lesson plan could be very useful, not just for kids but adults as well:

via Nidhi Reddy, Math Pioneer Fellow at Khan Academy:

When I’m working with new students, I’ve often heard them say, “I’m just not good at math!” Many people believe their intelligence is “fixed” and they’ll never be able to improve.

But research has revealed that students who develop a “growth” mindset, recognizing that they can develop their abilities through hard work and dedication, have greater motivation and success than students who believe that intelligence is “fixed.”

I worked closely with PERTS, Stanford’s research lab on academic mindsets, to create a lesson plan to help students build a growth mindset. This lesson includes activities, links to additional resources, and posters. Please feel free to adapt it for your own students.

Again, you can download it here.