My Teacher is Crazzy (6.EE.1 AND , MGSE6.EE.1 AND 2 ): Youtube video that could be used as introduction to variables, writing expression, and evaluating expressions with assigned values.
Mr. X and Value (6.EE.5 AND , MGSE6.EE.5): A poem that explains how solving for the variable provides a value that will keep the equation balanced.