We're making Mac and cheese today.
Classic béchamel foundation and then make it into a cheese sauce.
I say several times during my demo that the béchamel needs to cool a bit, not a lot, but it can't be straight from a boil then throw in the cheese. I made it a point to rest the béchamel for maybe 60 seconds and then only added about 1/4 C of cheese. I talked about tempering and the fact that cheese is milk solids and fat and it will separate if too hot. I added another 1/2 C and stirred until melted. I broke it down to adding the cheese to 4-5 portions. And patiently stirred until the sauce was creamy and smooth.
EVERY kitchen knows better than me. All six groups dumped the cheese into the béchamel while it was still on the burner. All six groups had gritty, mealy cheese sauce.
"This recipe sucks!"
Teenagers suck!
::end of vent::
Did you take the opportunity to say, "I'm sorry the recipe sucks! How many of you followed the instructions I modeled in the demonstration?"