Students are checking each other homeworks. It takes only 1 minute. I don't have to go around and stamp. I collect homework only once a week. This is how it is being done: In the beginning of class they check if the homework of other person is completed in a group of three or four clockwise direction first, in a week or so, counterclockwise. The rules are very specific about what do I mean by homework to be completed. It is written on the worksheet. They give each other -1 or OK and sign their name.At the day of collecting weekly homework students staple this sheet(should be colored) to the front of their hw packet and turn in. If they had two of -1, I will subtract 2 from the total.