You really don't want to try to retain ownership of that type of equipment, but once you donate it, the stuff DOES belong to school/district to use as they see fit, including reallocating.

Your approach is a good one in that it tries to clarify the source of the equipment, so perhaps they will think twice.

I don't think it would make a legal difference, but it might invoke some common sense concerns.

This is something that totally broke our hearts when we did it - so want to warn others. A parent group in which I was involved raised money to put a television in each classroom. Later that same year when doing inventory - the district came in and said they needed the TV's for other buildings in the district and took them. These were "gifted" to the school from the PTO and therefore technically were the property of the school. After raising holy you know what, we learned that legally they were not OUR TV's as we had in fact given them to the school. Labels were subsequently purchased and attached to everything we bought stating that this property belonged to the students of __________ school and funded through support of the families of that school. Don't know if that will hold water either - but it made us feel better, and the problem didn't come up again. I am no longer at that particular school, but have convinced the parent organizations of the two schools I volunteer in now that this is good practice. Just a thought to pass along to others in the same situation.