A really interesting article from a few years ago about a tribe in the Brazilian jungle that doesn’t have words from numbers past four. What are the implications of this linguistic limitation? Does this inhibit their ability to do math or to conceive of mathematical concepts?
Here is a handout I made to introduce the Mayan math system that allows them to do some simple calculations.
Here is a great interactive feature which talks about the Mayan math system and how it allows for complex math to be done in simple and intuitive ways.
And a great TED Talk about the value of rituals and beliefs.