Students may need help not only manipulating their backpack but also problem solving how to acsess the fasteners and put their back pack on.
Make sure the student can reach his backpack hook or locker
If the student has difficulty using a zipper, try attaching a large tab for easier manipulation.
Teach the student to use non-dominant hand to stabilize the backpack while pulling the zipper.
Suggest that the student reduce the load being carried by bringing only necessary items to and from school.
If the student's backpack is too heavy, awkward, or large to carry on their back, suggest to the parents to try a rolling backpack.
show how to put arm through and then have them copy your step by step example.