Is "What he threw surprised me." correct?

[popri]

Other students and I were trying to make some sentences with noun clause using "what".
e.g.) This is not what I ordered.
I can't understand what you are saying.

A student made a sentence as follows.
What he threw surprised me.

I feel kind of awkward when I read this sentense. I feel what-clause is used for something vague such as idea and thoughts, but I'm not a native speaker.

1.So could you please tell me if the example is correct or not?
2.If it is not a proper English, how do you usually say the example sentence, instead?

Thank you in advance.

[5jj]

This is not what I ordered.
I can't understand what you are saying.
What he threw surprised me.

All of these are fine.

What you wrote is fine.
I am happy with what you wrote.

[popri]

Thank you so much for answering my question.
I was not sure about what I wrote, but I'm able to have confidence about them thanks to you.