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Using Key Words: A Bad Math Strategy?

I remember back in college taking a course called Mathematics For Elementary School. One of our group assignments was to create posters (now called anchor charts) of problem solving strategies. I don't recall what my group came up with but at least half of the class made posters showing "key words" for solving word problems. Apparently this was A-ok with our professor because they were hung all around the room. You know the kind of posters I'm talking about... 

 

Teachers still have charts like this and still teach kids to use key words. I'm here to tell you to stop, or at least be very careful when teaching this as a strategy. Here's why...

 

When you teach kids to look for key words, you're teaching them not to think through the problem completely. Looking for key words is way a to opt-out of thinking through the problem from beginning to end. Children who have been taught the key word strategy usually don't study a problem. They don't think about what it means or what is happening or how they could figure it out in real life. Instead, they scan through the problem, searching for those all-important key words, until they strike gold. Then they use whatever operation "goes with" that key word... even if it doesn't make sense. 

 

Let's test out some of the magical key words...

 

"IN ALL": This means you should add, right?

  • Mary had 12 candies. She bought 7 more. How many did she have in all? Easy! 12+7=19 candies. Maybe it does work...

  • How about this one... John bought 7 cartons of eggs. Each carton contains 12 eggs. How many eggs did he buy in all? Umm, 7+12=19 eggs?

  • 75 people visited the museum on Sunday. Twice as many visited on Saturday. How many people visited the museum in all? Oh no, what do I add? There's only one number!

"HOW MANY MORE?" Time to subtract!

  • The third grade is going on a field trip. 44 students fit on the first bus. How many more buses are needed for the other 70 students? Hmm... 70 - 44 = 26 buses. That seems like an awful lot of buses!

  • Sam went to a movie that started at 2:45 and ends at 4:10. It is now 3:30. How many more minutes are left before the movie is over? Uhhhhh....

These are just a few examples of why key words often don't work. It gets even messier when students are asked to explain their thinking or to draw a model, as they so often are on today's assessments. Not only do they get the wrong answer, but the only explanation they can come up with is, "Because the problem said 'in all' and that means you add."

 

Now, this is not to say key words can't be helpful at times. But teach other strategies first

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