Do everything without complaining or arguing, so that you may become blameless and pure, children of God without fault in a crooked and depraved generation, in which you shine like stars in the universe. Philippians 2:14-15 (NIV)
Here is a very simple activity for these verses. Not a craft, exactly.
Put a dark background (like a dark sky) on the wall, bulletin board or white board. Let each of the kids make a big star with their name and or picture on it. Make the stars out of construction paper with glitter or a shiny stiff paper or foil. Velcro or magnetize the back of each star (or use a felt back and felt stars) so the star can be put on the board and taken off the board repeatedly. When the stars are finished they all go up on the board. When a child whines or complains the star comes down. When the fallen star does a task without whining or complaining the star goes back up. You don't even have to talk about it.
There's probably a way to go more hi tech if you have the skills. Cut the stars out of dark paper hang it on frame. Put a light source behind it. Use dark paper pieces to cover the holes to block the light instead of taking the stars down. The advantage of this version is that it shows how more stars mean more light in a dark sky.
Whichever form you use keep the board up and use it for a number of weeks 'til the kids stop thinking about it. Then, if you really want to make your point pick one activity you know your kids are going to love and one activity that you know they're going to hate and see what happens to the star wall but (as teacher) don't say anything! Tailor it for your age group so you set them up to succeed and understand, not to fail and lose interest. Timing is everything.
Play with it. See where it takes you.