This video ranks #4 because it is too long. It is 15' long. The first 6 1/2 minutes are an explanation that covers how algebra tiles are named. Only then does it explain how to simplify expressions. When the teacher creates zero pairs, he does not remove them, but leaves them circled in pairs. Fifteen homework problems are assigned and displayed at the end of the video, but they are "drill and kill" poblems rather than higher-order thinking problems.
This video ranks #3. It gives two examples of simplifying an expression using actual algebra tiles. The teacher uses his stylus to scribble out zero pairs of tiles and circle the remaining groups of tiles. Next he writes the original expression algebraically and then rewrites the terms to demonstrate how they can be simplified to the algebraic expression that represents the remaining groups of tiles.
This video ranks #3, because it moves too slowly. Time is wasted while the teacher drags each tile to its starting position to represent the given algebraic expression. Then he slowly drags together the zero pairs. I like the fact that the teacher presents one homework problem based on the video demonstration. He gives the answer orally after about a 10 second pause. My #1 ranked video got the job done in 90 seconds. This video took 6 minutes,
This video ranks #1. The teacher builds her expression on an expression mat with positive and negative regions, just like in CPM. She uses virtual algebra tiles with the same color scheme as CPM tiles. She demonstrates distribrution by flipping tiles from the negative to positive regions of the mat. Then she makes zero pairs and combines like terms. She writes each expression algebraically as she creates the newly simplified expression with tiles. This video is the most concise of the four. Yet it covers more simplification concepts with the most clarity: distribution of a negative number, making zero pairs, combining like terms, and representing tiles algebraically.