This can be used as a warmup or as an activity during class. You need to teach the grammar first. The key point is that just and already are interchangeable unless its clear that the event has occurred some time ago, in which case you need to use already. Nothing groundbreaking here, just a quick way to review.
This is a quiz with 10 questions.
I usually have students take a notebook or spare paper and write their answers. They can then mark it themselves. At the end, I usually give a sticker to the top three students. Of course, you can run it however works best for your students- could also work as line and row.
Really good review quiz. Thanks.