Here is a worked example of how we will be adding two 2-digit numbers today.  We will relate it to the diennes and focus on adding the tens and ones.  

Adding two 2-digit numbers crossing ten

But what about if the ones add up to more than ten?  We will discuss the fact that ten ones is the same as one ten.  Here is a worked example of how we will be solving additions where the ones add up to more than ten.