If the student is a minor, his/her parents would have to sign, not the minor him/herself.If the docuument is properly signed, it offers some, but not total, protection: it should shield the instructor from suits based on ordinary negligence or carelessness, but will not protect him or her from liability based on gross negligence (more than usual carelessness, such as expecting a beginner to do a difficult arial move), dangerous conditions of which the instructor is aware (like a damaged balance beam with a jagged edge), or from intentional acts (like hitting a student). Good insurance coverage is strongly recommended.