No Key Words
2. Don't use the key word strategy.
The Understanding the Standard section of 5.4 states, "In problem solving, emphasis should be placed on thinking and reasoning rather than on key words. Focusing on key words such as in all, altogether, difference, etc., encourages students to perform a particular operation rather than make sense of the context of the problem. A keyword focus prepares students to solve a limited set of problems and often leads to incorrect solutions as well as challenges in upcoming grades and courses."
In short: Don't teach students a list of keywords and their matching operations.
An Example
Mrs. King has 25 books to give to 8 students for summer reading. If each student gets the same number of books, how many will she have left?
If a student was taught the key words strategy, they would likely immediately find the words "have left". These key words usually signal subtraction, so what would the student do? Subtract 8 from 25, get 17, and not think twice.
If a student was taught to make sense of practical problems, they would probably start by reading the problem several times. They might make a mental image of what's happening, draw a picture, or get out 25 counters in order to model it. They would notice that each student needs the same number of books, which would signal a fair sharing problem. They might then deal out their 25 counters, giving each person 3 of them, and realize that 1 is left over. They would hopefully then go back and reread the story, checking to make sure that 1 left over book makes sense.
Not Convinced Yet?
If you're like me, you've used this strategy before. However, this is one of those cases of when we know better, we do better. Many well-respected math educators have written about the risk of relying on key words. Check out some of the resources below for further explanation:
Operation Sense is the Antidote to “I don’t get what they want me to do!”
Why I Don't Use Key Words (Or CUBES)
A collection of practical problems in which key words are misleading
So What Do We Do Instead?
The real key lies in sense-making and developing a strong understanding of each operation. Each of the first three articles listed above explores different strategies for sense-making. You will also likely find the Problem Types, Models, and Numberless Word Problems & 3-Act Tasks pages on this site to be helpful as well.
If you're looking for an even more in depth resource, I recommend Mathmatize It! Going Beyond Key Words to Make Sense of Word Problems. I read this book this summer with a handful of teachers at RSP and found it to be thorough and useful.