The blog dy/dan by Dan Meyer has a post titled
This has a comment thread of math teachers who blog and apparently regularly follow dy/dan.
Number 7 Jeanette links to
This in turn links to
Clicking on Algebra I we get
Page 5 of 8, we can cut and paste
The important point being the use of recursion. If we recall the Keith Devlin saga on repeated addition, that series ended up with Keith Devlin saying he did not advocate teaching recursion in K-12. Yet here it is on the common core standards.
The text Pre-Algebra New Math Done Right Peano Axioms does teach recursion at below college level to define addition of natural numbers.
Here is the Devlin post from Nov 2011 on recursion as part of his multiyear series on this topic.
ASIDE: This is not an article about mathematics education. How teachers introduce addition and multiplication is another issue. I am not, repeat not, suggesting we teach recursion in the K-12 system.
As we see from the above, the Common Core Standards do in fact suggest we teach recursion in the K-12 system. Devlin’s post then makes it clear that if we do teach recursion, we should do it right. This is what my book on Peano Axioms does. It is the first below college level text on the Peano Axioms.