I suppose it depends on your level of experience. I did the Level 2 and then the level 3. But if you'e a complete novice then starting at Level 1 might be best.
I did ask the instructor what Level 1 was like. He said it was pitched at this standard:
"See that big thing over there? That's a boat, that is. See the thing hanging off the back of it? That's an engine. it makes the boat go."
He may have been kidding.