In addition to the items in the Required Documents section, you should include:
Copies of all previously issued Forms I-797 showing H status
Evidence that you have maintained valid H status (e.g. a letter from the H-1B employer confirming current employment and three most recent pay stubs)
For H-4: copies of spouse's or parent's H-1B immigration documents: passport, Form I-94 (front and back), Forms I-797, and three most recent pay stubs.
If you are in H-1B status, you must stop working once the change of status to F-1 student is effective.
You may begin classes while the change of status application is pending; however, you are not eligible for F-1 student benefits until the change of status is approved.