Jose and Joselo were our only students this week so we weren't able to do many group activities. But at the end of class, they each had to make a list of items they wanted and their price.
Ex: 4 bags of flour. $5 each
Then, they had to ask each other what they wanted. Joselo kept on saying 'piece of cheese' when he wanted more than that he would still keep it in the singular form though. Jose was trying to correct him by asking him to repeat but Joselo didn't catch his error until they compared list and he discovered it. A good lightbulb moment. When we let students take the time to continue using English and then they find the error between themselves, the correction sticks better.