Glasgow Science Centre hosts many events, exhibits and has lots of great online content, as an example of the great work they do- they have a series of videos talking about science with a Scottish accent (I think this is a great way of making science relatable for the kids).
Located near Banff (in the North East of Scotland), this aquarium showcases aqua life from the moray firth. It also has daily feeding shows- which are great fun for adults as well as children. It makes a great stop off on a road trip or a day trip for locals!
A personal favourite on this list is the Botanic Gardens in St Andrews (this is the place I studied for my undergraduate degree- so I might be a little biased!!). This gardens has loads of weird/wonderful plants and the entrance fee is extremely cheap!