David worked with me at a sixth form college where he was the head of science department. David has a PhD in chemistry and has vast amount of knowledge and experience in the teaching and assessment of this subject. He is an outstanding teacher and unique knowledge about the subject. He provided tutoring for one of my fried's son who had achieved D grade in chemistry prior to the private tutoring with David and achieved B after attending tutorial with David. I would gladly recommend him for any tutoring opportunity.