I strongly suggest you leave off the second paragraph and don't express annoyance. I'd also avoid "very clearly" as it has a scolding tone. Students aren't perfect. Accept it. 

But the second paragraph should remind them that the time is getting late to work on the next essay. Suggest they get to work on it. 

I'd think you would be more successful overall with students like this to take a somewhat tolerant attitude and laugh at their marginal/poor behavior.