Let's present it in the way that matters.
You're not in school anymore, you're at a job. We decided that after our story boarding session, we want to build out more of scenes 10 and 11. Please make storyboards for those.
Instead of doing additional storyboards for scenes 10 and 11, you do an amazing set of additional storyboards for scenes 6 and 12.
Guess what? This wasn't what I needed, you need to follow directions better. I'm probably not firing you, but now I'm forced to micro manage you because you're untrustworthy. I will fire you next time.
I'd argue it's better for you as the student to learn that paying attention matters vs learning through the experience of being fired for incompetence.