We've been practicing applying the distributive property and combining like terms in Algebra 1. I want my students to realize that they can only combine like terms if they are on the same side of the equal sign or inequality symbol. This is a mistake I've seen students make over and over and over in the past few years.
Here's some notes I typed up for my students to glue in their interactive notebooks:
From the comments I received on Twitter when I posted this for #Teach180, it seems like once we start solving equations that this strategy will make students' work easier to check. That makes me super excited!