This is the outside of the foldable.
They start by drawing lines to separate the expression into a string of terms. Then they use a different color highlighter for each group and then they rewrite all the like terms together and simplify.
Kids always want to "keep going" at step 4 up there so I try to stress that however many boxes we have is how many terms there are going to be in the answer in the end.
During the school year when I have more time with the kids I would usually do this on day 2. I did an activity last year that I really liked where I gave each kid a strip of paper where they wrote an expression. Then they highlighted the terms, physically cut the expression apart, collected like terms, and then combine each group into a simplified expression. It was a really nice tactile way of doing this and I had them make posters with their examples that I hung up. It went well and it's something I plan to do again this year.