The remaining paragraphs have few pitfalls. The true test of this writing assignment is in the body of the piece.
Students tend to get into a rhythm and beat it to death.
I'm talking about variety. In the second paragraph be sure they don't list the tools and ingredients between commas in a single sentence. Insist students break those parts up, limiting them to perhaps two items per sentence. In the third paragraph variety becomes a matter of clarity. There can be no confusion about the procedure involved.