I do? I understand?

Whenever there was this Workshop class at school, I used to get all tensed up. Ah, no, it was not only because I could not just sit in the back benches and sleep, as I did in other classes, though that too was a contributory factor. There was this board in the workshop I hear, I forget I see, I remember I do, I understand Jolly good, I supposed, for all the people who had this