This is a great lesson that I have done as a group activity. I put the students into four groups (or two sets of four groups to make group sizes smaller). Each group has the "work page" that includes guided questions to help students build their equation. Each group begins with one word problem and spends about 3 minutes writing an equation and solving. After time is up, I have groups switch word problems until each group has worked on all 4 problems. We end with a discussion, or I pair groups together to discuss their solutions. More word problems could easily be included.