Friday, January 13, 2017

Teaching Percent of a Number: Is that the answer? I don't know....what is the question!

    I have been teaching percent of a number for the last couple of days.  As always when I teach this topic, I think that actually teaching the kids to find percent of a number is less than half the battle.  I used to teach the kids to change percent to decimal and multiply.  In the last several years, however, I've really become a fan of either percent tables or proportions.  I think they set the kids up to understand better what their answer means, and how to be flexible in working from that answer.

      Some years I have some percent stations that I use to introduce the kids to the different methods, but this year we used a pretty simple graphic organizer.  After going through a few problems together, they seemed to really be getting the hang of it....the math of it, that is!
percent tables #percentofanumber #modelwithmathematics
This is an example of one of the percent tables that we use.

      However, I can't tell you how many times I've been asked in the last two days, "So is that my answer, or do I have to add (or subtract) to get the answer?".   We talk many times about how reading plays a role in getting these questions right.   When a kid asks me that, I usually ask a question in return:  "Does your number answer the question?" and I read it back to them.  The tough part is that when I talk with kids, that makes sense, but then applying it on their kids need something more.

     So at the moment, I'm feeling reflective, trying to think of ways to help this make more sense to my kids.  Here are 3 things I think I'm going to try....
percent of a number #erroranalysis

     1.  Highlighting---I think for my more visual kids, it might be helpful to highlight the percent in the problem, and what the answer is asking for.  Then students could look to see if what the question asks "matches" what the question gave them....if not, they need to do something else to get their answer.
percent of a number #storyproblems

     2.  Silly answer skits---I tried this once last year (with a different topic), and it was fun.  We basically turned a story problem into a short skit, and then acted it out with their "wrong" answers.  The last time I did this, it was based on the problem below.  When trying to answer the question how many peppers can you buy for $9 (which is right in the table!), many of my students told me the cost of 9 peppers.

So I thought if I had the kids act this out, they might realize their mistakes.  Here is the script we used.
When we acted this skit out, I think many light bulbs went on for students....helping them realize that their answer had to make sense.  I think I could use the same strategy for these types of problems. For example:  "Tax is 6%, book costs $10.  What is the total cost?"  I could have kids act out trying to buy a $10 book with only $0.60!  

     3.  Sorting cards--I'm excited about this idea.  I think I'm going to make my kids a card sort.  So, for example, if they have a card that says 6% tax, book is $10 then they will have to find cards that say $0.60 tax and $10.60 total cost.   I guess I know what I'll be doing this weekend.....making a card sort!

UPDATE:  I finished the sorting cards....can't wait to use them!


  1. I can totally relate to the struggle here! Getting students to make sure the answer matches up with the question can be a challenge at times. I love your skit idea! I bet that really gets the students thinking about how questions and answers match up!

    1. The look on their face when they realized what they had done was perfect!

  2. Acting out math problems is a great idea!