Buy more than you think you'll need and turn the leftovers into tomorrows lunch or freeze. I'm cooking 14 chicken drumsticks tonight, which will feed four of us with a little leftover if I'm lucky. Last night we polished off two racks of pork side ribs. 1 pound of hamburger is barely enough for a meal with no leftovers.
When my kids were that age we just cut a few bites of meat off of our serving for each of them. Now they are nine and 12 and both eat adult sized portions of meat.
Since we hunt or buy most of our meat by the half or quarter I buy very little grocery store meat on a weekly basis. our grass fed beef comes in around 5.50 per pound. Wild game is much cheaper.