I encourage you all  to WATCH this video: Reteach and Enrich: How to make time for every student.
The video centers around a group of teachers at a school in the town of Mesquite in Tuscon, Arizona. The video reveals an excellent strategy their school employs to make sure no one falls behind and each student is reaching the objective for the week. Each week the teachers decide on the objective (based on outcomes and indicators) and students take a short exam on the objective at the end of the week so teachers can assess whether or not they achieved the objective. If the student did achieve the objective they get put into the "enrich" group and those who didn't are put in the "re-teach" group (this is done across the stage so one teacher can take the "re-teach" group and whatever teachers class had the most students in the "enrich" group got to take that group, as they obviously had a good way of teaching the subject due to the amount of students who passed that particular objective. There is then a period of time where they teach these groups the following week, so every week half an hour is dedicated to reteaching and enriching, so the students who just didn't quite get it, get another chance to reach the objective and those who did "get it" are able to have their learning extended. 
That is the basis of the strategy, please watch as you get a really good idea of the strategy and see just how practical it is! What I love is that each week you have different kids in each group. One week Timmy might have not passed the test on say long division and was therefore was placed in the "re-teach" group but the next week he might have achieved the objective in fractions and then be placed in the "enrich" group. So kids are always changing groups and don't feel downhearted, the teachers in the video have made it clear that both groups are positive, and "re-teach" just means you need a little more help in that area. 

Oh my gosh, so very sorry for the rambling! I was processing the strategy in my head while typing so its probably mush. So please watch the video to fully understand and see how wonderful this is. 

Thank you lovely teachers, 
Jordie