Math Struggles

I have asked my principal for permission to not use the math workbooks and to just try using the Montessori materials and lessons. I was granted permission with the condition that if I saw it wasn't working to go back to the traditional material. So I am giving the chapter tests and trying to use my Montessori materials to teach the material covered in each chapter in addition to the sequence of Montessori lessons and individual work time.
I gave a pre-test of chapter 2 hoping I could move on but many children did not understand the concepts. So I have been doing partner work and lessons on making quanities.
I have one group (maybe half) that "get it". The others I am a little frustrated with as they are still having to count the 3 bead units and don't "see" that 1 bead and 2 beads make 3. Even though we have been writing number sentences with sets, they still don't get that their first number has to be how much is in their first set. Am I just expecting too much? I know they didn't have Montessori preschool or Kindergarten but I really thought that being 6 and 7 this would come much faster for them. Any thoughts?

We are Working!

I finally have work time going for all my class now. I started it slowly by having the ones who finished their traditional classwork choosing work to do from the shelves. I have run out of shelf room (I ordered the teen and tens board set from Sue at Montessori Steps). Really nice sets that came with cards you can use as 3 part cards. I'm going to have to figure out how to rearrange some things to get more room. I am in the process of making my traditional tasks from the past two years more Montesssori-ish by adding control cards. For these items I am using my drawers from last year as I am out of space. It works pretty well. Each child has a colored folder and the folder corresponds to a drawer. In their folder are the response sheets for tasks I want them to do. They match the sheet to a miniature version of it on the manipulative/hands-on material it goes with. For example, for pink series word work I put the pink word work book in the child's folder. They go to their drawer and in it, they will find a pink book attached to a ziplock bag that contain the picture and word cards, a control chart, and photographed instructions for what to do. They take the ziplock bag and word book to their choice of work space and do the activity.
I am using a folder system right now, to ensure that all students are working on something on their level. I have a checklist of their "have to's" that I check off when they complete. I use a 3 "have to's" and then choices system. This also keeps the children from fighting over the most popular choices as they finish at different rates.
I would love to eventually go to an all choice work system, but as this is all new for me, I feel the need to take baby steps.