Saturday, April 30, 2016

Teaching Two Digit Addition Strategies

Two Digit Addition Strategies


Hi, it's Jane Feener dropping by to discuss some of the ways I have taught two digit addition strategies in my class this past month.  I can now finally say that I have learned how to do it using all the various strategies that are being shown to students today.  Before moving to second grade the only way I knew how to add two numbers was with the good old traditional vertical algorithm that I was taught in school.  Now, my students tend to chose their own ways and I am okay with that. 



Use a blank number line



This one I thought would be confusing for my students but most got it right away.  I think they liked the idea of hopping along the line like a bunny.  If you were adding 46 + 35, you would start with the largest number and place it at the beginning of the blank number line and then you would make 3 large jumps for the 3 tens.  Next, you would make 5 smaller jumps for the 5 ones.  The students count by 10 first and then by ones to come to the answer 81.  As long as your students can count by 10's this strategy works well.


Use a hundred chart


As long as students have a hundred chart at their disposal, this strategy is a great one to use.  My students have name tags on their desks that contain a small hundreds chart so I often saw them referring to their chart.  I also had large hundred charts copied and laminated for my students to use.
If they were adding 46 + 35 on the hundred chart, their first step would be to circle the largest number which in this case would be 46.  Next, they would move down vertically 3 rows for the 3 tens and then move horizontally to the right for the 5 ones to come to the sum of 81.  When I taught this I made squares around the tens and circled the ones just to give students a reminder that they were going down by tens and then changed to the circles to show the ones.  I also used a marker to put arrows on the the hundred chart to help those students who needed a little reminder.

Use place value


This strategy took a little bit more explanation but once students figured out how to decompose the numbers into tens and ones, they were experts at solving sums this way.  I know the poster may look a bit complicated but I found that by using circles and squares for the different place values helped my students.  My students also liked drawing the arrows.

Use base ten blocks


I found for any of my students that experienced difficulty with adding two digit numbers, that this was the best strategy to start with.  I worked at the small table with students using the base ten blocks to solve various problems and it was wonderful to see little lights coming on in their heads as they started to figure it out.  I had a few students who I gave a small ziploc bag of base ten blocks for them to keep at their desk and use as needed.

My students really enjoyed singing and dancing along to this YouTube video as well.  These teachers are great!                                  

You can find a copy of these posters and a booklet with an answer key to practice each strategy here.


Two Digit Addition Strategies Poster and Booklet
You can get this free poster of the more traditional method of two digit addition in the preview.  Just check here.


If you have any other videos or tips you use to teach Two Digit addition, I would love to hear about them.  Now I am off to learn all the different subtraction strategies!




2 comments:

  1. Why didn't I think of those before. Thank You for introducing these various methods of teaching 2 digit addition. Will surely be introducing these to my next set of second graders in September. Looking forward to the subtraction strategies.You're amazing!

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