Formalizing the relationship between teen numbers and equations of the form 10 + n.

Solving simple story problems involving teen numbers using the 'ten and some more' structure.

Using visual models to compare teen numbers and determine which is greater or less.

Introduction to unitizing: seeing 10 ones as 'one ten' using bundles and towers.

Breaking apart teen numbers into 'ten' and 'some more' to prepare for equation work.