For myself, I want to keep track of how these things go by writing about them here.
Today in physics, I had some problems straight out of the book that I wanted my students to do for practice. My students are always sitting in pairs, so I put the problems in groups of 2. The idea was that each partner would complete one of the problems and then they would add their answers together.
I had the sum of the answers written on the board, like this:
Partners check their sum to see if it matches. If yes, hooray! If no, they must examine BOTH problems to try to find the error. And, hopefully, productive discussion happens.
What I love about Add Em Up: The students were working harder than the teacher! It is super easy to implement. I didn't have to create anything new, all I needed was the set of problems that I had already planned to use for practice. Most of all, I love how it allows the students to self check and correct without directly telling them the answer.
What I don't love about Add Em Up: Nothing, really! The only problem I encountered was that one student ditched his partner part way through. He got the idea that he was only accountable for the problems in his column and he started checking with the person behind him and letting his partner (who was having trouble) fend for himself. I blame that situation on myself, since it was more of a classroom management issue. I realized it was happening when the ditched partner started asking me for help. So I talked to the first student and hopefully got that straightened out.
This one is going to be a regular in my bag o' tricks.