When you find yourself trying to remember a show (or any works) that's on the tip of your tongue but just out of reach, come here - the collective brain of the TVTropes community can probably help. Post all the details you can remember (examples help). If you're looking for a trope, head over to Trope Finder. Have general questions about tropes? Visit Ask The Tropers!
I honestly don't know how well this fits because I barely remember the game myself, but it's the first educational game with pirates that came to mind for me: Reader Rabbit Math 6-9? Here's a link, starting with the main map used for choosing minigames: https://youtu.be/b_oeTOu6PVA?t=4m
I don't think that's it. If I remember right, it was mostly text based so there were no voice overs.
Disclaimer: If anyone disagrees with anything I say, I am quite prepared to not only retract it, but also to deny under oath I ever said it.
So I'm trying to remember the names of these two PC games that I played in school. They were education based, one involved pirates and the other was about fairy tales (I specifically remember Little Red Riding Hood). The fairy tale one I think was maths based because I remember you'd come across a character who would give you some information and it was important for when you met another character down the line and they would ask you to repeat it back to them or use it in a maths question and if you got anything wrong, the game just ended and you had to start all over again. The pirates one was more or less the same.