Adding Decimals

Students looked at how to add decimals today.  First, we took a horizontal equation and attempted to correctly write it vertically then add it.  Next, we took the different answers and placed them on the board.  Then, students voted on the correct answer and volunteers came up to state their reasoning as to why they chose that answer.  Through our dialogue, opinions changed and through proofs students all came to a consensus as to how to write the equation and why, thus deriving at the correct answer.