For physics practicals of unit 3B...u should consider the practicals mentioned in specification and specially learn those in the hodder book..solve the past papers..u'l hv a good idea..specially read carefully through the examiner's report while u do the question papers..u'l hv a good idea of how to answer..:-) U can even read practicals from the implementation guide..:-) hope it may help u..Solve as many question as u can related to the practicals..Always answer to what is required,since time is limited in exams.