We are used to rolled eyes in this house. I've never quite got used to the groans, though.
At that point I had three choices.
1) start my usual long soap box drone about how much writing they would be doing if they were in school (noteably a lot more than filling one word in and sticking it onto a piece of cardboard) ending in me either sobbing or threatening to phone up the local school.
2) give up any thought of this 'jolly' activity, take on my autonomous parent mentality, and let them fry their brains on Minecraft for the day.
3) smile sweetly and carry on while sticking my fingers in my ears and going la la la la la everytime they complained about having to make a couple of marks on paper with a pencil.
Rightly or wrongly, I opted for 3. (But, being kind, I refrained from the la la la bit)