Episode 178: Students who struggle with Less Than problems

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Welcome fellow Recovering Traditionalists to Episode 178: Students who struggle with Less Than problems

This episode comes from a question someone sent in:

“I have a question for you…. Our second grade teacher came to me yesterday and asked what she can do to help kids understand this problem…. 86 is 10 less than?  answer being 96.  They don’t understand the way it is worded.  If it was… what is 10 less than 96, they would know it is 86.  Any suggestions?”

Those types of problems are tricky but especially because they have no context to tie the problem to.  For example, you can get at the same idea but through a problem like:

John has $86.  He has $10 less than Sue.  How much does Sue have?

So my recommendation is to use lots of story problems so they see the math in context to understand what is happening with the amounts.  This example I just gave is considered a “Compare with Larger Unknown.” 

There are 3 types of Compare problem types:

They do need exposure to the normal Compare Difference Unknown problems that include the wording with “fewer” and “less,” but those are a bit more common in math materials so it’s not something many teachers need to worry about adding into their resources.  However, the Compare with Larger, or Smaller, Unknown are not common story problem types, with the Larger Unknown being the least common which is why kids struggle with them, so make a point of including them.

My other recommendation is to use lots of visuals.  These types of story problems are often modeled with bar models where you draw a bar for John, or Sue, and then talk about what the bar for the other person should look like based upon the information in the problem.  

For example, in the original problem I gave of “John has $86.  He has $10 less than Sue.  How much does Sue have?” Students would draw a bar and label it as John’s with $86, then use the info in the problem to decide how to draw a bar to represent Sue’s.  John has $10 less than Sue…so who’s bar should be longer?  

The more students use these visuals to represent the contextual problems, then we can help them transfer that to solving them with the bare problems like the one sent in “86 is 10 less than?”

The answer to the question of how to help students with those types of problems really does boil down to two of my GO-TOs whenever kids are struggling with a math concept: 

1. Put it in Context
2. Make it Visual

Now for members of the Build Math Minds PD site who want more in-depth training on all the problem types, Ann Elise Record did a couple of great mini-courses about problem types for Addition & Subtraction and Multiplication & Division.  So if you are a member log into the PD site and search for Problem Types Mini Course.  If you aren’t a member, you can join at buildmathminds.com/bmm 

Alright my fellow Recovering Traditionalists, until next week keep building math minds!

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