Students are each given a worksheet and write a number in each space (I did 1~15 in my lesson). 

Students then make pairs and exchange the target English. Students can choose if they write their friend’s answer down or not. If they choose to write it, they cannot erase it. Once both students have done the question and answer, students make a new pair and exchange the target English.  Again, students can choose to write down their friend’s number or not. 

The goal is to get exactly 20 items. So if their friend’s number will make them go over 20, they cannot write the number down. Once they get exactly 20 items, they score one point. They start from 0 and try to collect 20 again!