Re: OP
OP Seems to think RAM is the solution, and missed that their School PCs have economic OEM drives in them. So the extra £50~ on the RAM could have been used on the SSD upgrade and it would work *faster*.
So yes, on a system with a slow HDD and low ram, it is slow. Upping the ram allows Windows 10 to use prefetch options. You just sped up the computers in the most expensive way. Adding a faster HDD or SSD would benefit them, possibly better too as actual disk searching and non-cached content will be fast.
Though of cause just a RAM disk is the fastest option. But not needed on most browsing PCs/Laptops, so 4 or 6gb is the average.
[edit] Sorry, seems they have known this, and are upgrading old tech, so ram is a penny a stick.