Have you tried doing the reverse. Show them the solution and ask them to form a word problem (based on the solution). It would show you how students parse (break down) word problems in their minds.
Start easy for example: x + 2 = 8 form a word problem using slices of pizza. The way the children form sentences will show you the words they use to define a problem.
It would also allow you to reword some problems using words that the children use, since it looks more of a language problem than a math problem.
Don't be strict in the child's sentence construction, the point is you want an insight into their minds of how they form, break down, and express math word problems in their heads. You will probably see word problems looking like conversations instead of properly structured math word problems.
Once you have a common ground you can later show them what a properly structured word problem looks like - with emphasis on buzzwords as suggested by Andrew Sanfratello - allowing you to compare buzzwords to the words your students use.