[piersklein]

It would seem to me that you are still affiliated with the school but not with the head of the science/engineering department. Given that the administration had to approve a parent as lead contact, I think that the school is in charge of the team. If this is the case then there is very little chance that the teacher is able to actually prevent you from using the tools and space. In every district, the use of buildings is under control of administration and School Committees rather than individual teachers. I would suggest having a meeting first with the principal of the school (and the superintendent if you wish) and explaining the situation and what you want to do to best benefit the team and by extension the students. Afterwards, ask for a meeting with the principal and the teacher with the goal of coming to a solution that is beneficial to the students.

I do disagree with some others in this thread about what is appropriate. In my opinion, you have a teacher who is intentionally and blatantly harming the educational opportunities of the students and because this teacher is in a position of power, nothing can be done without the administration. The school principal and superintendent do need to know that there are students in their school who want to further their education and are being prevented by the whims of a teacher.