First, let's talk about the basics. It's a much bigger campus and there are anywhere from 600-850 kids on a middle school campus versus the 450-600 in an elementary school. The size varies significantly from state to state For example, the average middle school in Florida has over 1000 kids. 1000 kids!
The 6th graders, formerly the "big fish in their little ponds" are now feeling inferior and crises of confidence can erupt. Their fears become exaggerated and their coping skills may fail them. At this time, parents, you cannot tell them, "You'll be fine". It's important to accept their feelings of angst and give them options for how they plan to cope with these new challenges. Give them "scripts" for responses and practice/role play frequently depending on the level of anxiety they're feeling. Provide support only to the level they are willing to accept. Don't overdo it just because you are anxious.
Speaking of which, teachers are incredibly, incredibly over-worked. They have 100-120 kids. Yes, 100-120 kids. If your child has an Individualized Education Program plan (IEP) or Section 504 Accommodations, don't assume that the teacher knows anything about it. Records coming from elementary schools are frequently late and chances are, your kids' actual teachers did not attend the transition meeting. Make a Fast Facts sheet and let them know a little bit about your student.
Your child may have special needs that do not rise to the level of a diagnosis or the need for special education services. If there is an illness in the family, teachers need to know. If there have been extraordinary situations such as death, divorce, moving, a family member deploying, a pet dying, or a parent returning to the work force due to financial demands or anything you qualify as "teachers need to know", then, create a Fast Fact sheet. Make it easier for teachers to help you help your child.
Accelerated and summer school classes move at a very fast speed and do not allow students to practice the concepts to a level of automaticity (meaning quick recall and solid competence). It's critical that students have multiple opportunities to both learn and practice the concepts and algorithms before moving onto more advanced concepts. If it's right for your student, then go for it, but approach with caution.
Once kids fall behind in middle school, it is extremely difficult to make up the grades because the overall pace of "production" (the amount of work that is produced), is quick, to say the least.. My metaphor is gaining weight and going into debt. It happens oh so easily, but losing weight and getting out of debt require commitment, discipline and persistence.
I wrote extensive blog posts on the special education referral and the special education assessment. Educate yourself about the process and do your best to get the help your child needs.
As always, just do the best you can.