The objective that I am trying to teach is to write and solve a one-step equation from a word problem. I don't mean the "the sum of x and 4 is 10" kind of thing. More like, "You give a cashier $60 for a pair of shoes. The cashier gives you $8 in change. Write an equation to find the cost of the shoes." What I want them to write is 60 - x = 8 OR x + 8 = 60. What the students want to write is 60 - 8 = x . Can anyone help me explain why they can't do it their way? Thanks!

Their way works, in fact: total tendered minus change equals cost. Why do you need them not to do it that way?

I agree. If you want the kids to think of it as an addition problem re-phrase it: John has $8 saved. He wants to buy a video game costing $60. How much more does he need to save?

On the STAR test, they will be required to identify which equation will give them the correct answer (with none of the choices being 60- 8 = x), so I thought that by learning to write the equations on their own, they would be able to identify the correct equation more easily. I appreciate the suggestion to rephrase the question. I may go beyond that to say "Write an addition equation that will find the cost of the shoes." Thanks!

As opposed to rewriting the question what if you asked them for 3 different ways to write an equation for the problem. You may have to give them less problems to answer but at least they would have to think about multiple representations of the same problem. They would come up with the simplest version first, 60 - 8 = x and then have to derive others.

I think SreevesTX's solution will serve your students better, Dutch: it's a tremendous help in test taking to be able to recognize and use alternative ways of phrasing an answer.