I just wanted to stress the importance of teaching the "Packages and Groups" unit. I've heard from TERC people that originally they developed one unit on multiplication and division for grade 4, but it got really big so they split it into two units-- "Arrays and Shares" and "Packages and Groups". So "Packages and Groups" is a very important continuation of the ideas in "Arrays and Shares" and if you don't get to both units, you haven't really covered the important ideas of multiplication and division for grade 4.
