Think about the following word problem:
Brandon took 6 baseball cards that he no longer wanted and gave them to Benny. Now Brandon has 10 cards left. How many baseball cards did Brandon have to start with?
When we think of the word left, we typically associate it with subtraction. In the word problem above, however, addition is the operation that you would need to use to solve the problem. Teaching kids to rely on key words doesn't encourage kids to visualize the problem and think about it's structure. It merely teaches kids to hunt for words and solve without making sense of the problem.
Here's another example of how key words can be misleading:
Megan made $25 during the bake sale. Afterwards, she had to pay $5 for renting the table. What is Megan's new total of money earned?
Again, kids would see the word total and automatically assume that they need to add. However, adding the two numbers together wouldn't give a reasonable answer. This is why we need to get away from using key words and instead focus on the structure of the problem. Acting the problems out and getting kids to visualize the problem is helpful (and fun!) for students.
In the Common Core standards, teachers are encouraged to teach students the 5 common addition and subtraction situations. I like how this statement focuses on the word situations and not key words. The five common situations include: add to, take from, put together, take apart, and compare. I try to use these terms with my students from the beginning of the year and they are really helpful. Here's a brief explanation of each of the situations:
Add To: an amount is added on to another
Example- "I have 52 baseball cards. My friend gave me 37 more. How many cards do I have now?"
Take From: an amount is taken from another
Example- I had 145 baseball cards. I lost 25 of them. How many baseball cards do I have now?"
Put Together: two amounts are put together
Example- Sam bought 67 baseball cards. Max bought 32 baseball cards. How many cards did both boys purchase?"
Take Apart: the total amount is taken apart
Example- There are 238 trading cards at the store. 100 are baseball cards. How many are not baseball cards?"
Compare: two amounts are compared to see how many more or how many less
Example- Walmart has 115 baseball cards. Target has 102 baseball cards. How many more cards does Walmart have?
If you'd like a free set of posters matching these situations, click on the picture below. Enjoy! (And throw those key words out the window!)
