How to implement differentiation in orchestra

I think it is impossible to keep an entire orchestra class at the same level.  There are always some students who practice harder and as a result they progress way more quickly than some students who don't practice or who struggle with position or note-reading.  I have been trying to find a way to target strengths and weaknesses of individual students and customize certain learning activities based on their needs.

As mentioned in other posts, I do not require practice cards, but I do hold a playing test every 2 weeks where students play alone for me during class.  In the past,  I have always had each student play the same test, no matter how advanced or how behind they might be.  I have finally found a way to differentiate for my playing tests so that I can have students practice and work on things that are more relevant to their current level of progression.

Today, I announced to all of my classes that they would have a playing test on Friday.   I assigned my advanced players a more difficult solo melody that we will play at our next concert.  I assigned one line from our method book to most of the rest of the class.  Then, for my lower-level learners, I made a specialized assignment and I passed this out to them individually.  My lower level learners will concentrate on instrument position and note-reading so that they can gain the skills they need in order to catch up with the rest of the class.

Here is the assignment I am using for my lower-level learners:

I made flashcards for each student using this template and stapled them to the Alternate Playing Test form:

I am excited to see how this will help my students.  I wish I would have done this sooner!