If someone in the Harry potter universe combined Muggle technology with magic they would become unstoppable. Really they should first learn to apply the scientific method to magic and do some research and development. The “Dark Lord” is very short-sighted when it comes to Muggle tech. If Harry Potter (or anyone else) owned a gun like a shotgun or Desert Eagle, then Voldemort’s dark reign would be short lived.
They also need to teach more (any) math, at least to Calculus (Maybe to Differential Equations). 🙂