Tens and Ones

Although many of our students know how to add double-digit numbers using the standard algorithm, sometimes the conceptual understanding behind the math gets lost or forgotten.  To warm up our double-digit addition skills in this unit, we went back to representing numbers using base ten blocks.  In groups of three, students chose the correct pieces to respresent two addends of an addition problem.  When they combined (added) their pieces together, they were able to identify whether they could regroup ten ones blocks as a single tens rod.  The banker helped them make the trade, and students could then identify the final solution to the addition problem.  Keeping this concrete process in mind will allow them to make greater sense of the more abstract process of regrouping ones as tens using the algorithm.