Good Lessons Sometimes Fail

Feb 16, 2016

Today was not the smoothest day in math.  Could have been worse.  But Jess and I were hoping for some light bulbs to magically go off.  That did not quite happen.

Some days are just like that.

We felt that our lesson plans were strong.  After the "I Can Teach Math" conference last week, we knew that we wanted to discuss the "distance" between numbers.  We really had not used that terminology before but it made a lot of sense when they discussed it at the conference in relation to part-part-whole.  Students need to have an understanding that subtraction is the distance between numbers.

We wanted to relate this concept to missing addend, as well.

And so the lesson began.

We started with a math story using a scene from a Little Critter book. The little girl blew 12 bubbles but the dog popped many of them and now there were only 5. I wanted them to see the parts of this story that made up the whole (12 bubbles).  So we used this Didax number line to fill in the part of the problem that we knew.

Then we added a different color of cubes to show the part of bubbles that we did not know (missing addend) or the part of the bubbles that were popped. I discussed that we were trying to find the distance between the part that we knew (5) and the whole number (12).

The words part, part, and whole were used repeatedly over and over again.  I wanted to be sure that I was connecting this learning to what they had been studying all year long; however, Jess and I found that still were not consistently able to tell us that the 12 was the whole. (Grrrr.)

Then I took this number line representation and connected it to a dry erase number line that they could write on.  We circled the part we knew and drew a line at the whole number.  Once again, we discussed the distance.  Some students were able to start at the 6 and count this distance and some wanted to start at the 1 (Grrr...again).

I am not really "grrr-ing" at the students.  It is my teaching that is the problem. It si not helping them to connect the dots.

So what do I do?  Well....we go back to the drawing board.  It needs to be more concrete and visual tomorrow.  So that is what we will do.

We stopped, listened, reflected, and now we are changing.


  1. It might help to have the 12 cubes laid next to the 5 that you know and count on to make up the difference. (Or to make them equal.) That is how I teach my kids to compare. I also call the number we are trying to find the "mystery number". In our number bond we write a big "?" Where the missing addend will go. It might make more sense if I could send a picture, but I am not at school with my math tools.

    1. Thank you so much for your comment! Today was much better bc we did more of what you are talking about. But I think I could do even more of it!! So I will add this into our lessons coming up this week! Thank you!!

  2. I have to admit that I haven't ever approached the idea of subtraction as "distance." I've been too cowardly. That word "distance" seems like such an abstract difficult concept. You figure this out, and then I'll tackle it. (See how cowardly I am?) :)

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