There are several reasons Quiz-Quiz-Trade is so powerful. First, it gets weary students out of their seats, interacting and talking about the content that we need to review, and probably having some fun as well. Second, students need to remember the correct answer to their partner's question because when they trade, that question will become theirs and they need to be able to tell a new partner whether they have the correct answer or not. Third, students have fun trying to stump their classmates with tough questions. These tough questions always spark student comment and debate about the content being reviewed, which helps to further etch the information into their memories. Fourth, it is probable that several students wrote similar questions. That means that your students are hearing the same information repeated over again, but phrased slightly differently each time. This also helps students remember the information.
For English language learners, Quiz-Quiz-Trade gives them practice asking and answering questions. It gets them to interact with their classmates, while having the support of being able to read the questions off of the card. Plus, the repetition and built-in redundancy of hearing similar questions in different ways adds to comprehension for ELLs.
To support students in writing their questions, you could give them some question frames like:
"What is _______________?"
"How are _______________ and _______________ different/similar?
"Why is _______________ significant?
The questions frames you use to guide your students will depend on the material being reviewed, your content area, the grade level you teach, and the English development level of your students. I only shared a couple of frames above. For more question frames you can see this page from the Reading Educator that groups question frames according to Bloom's Taxonomy (or you can do a Google search to find other examples, or spend the time to create your own).
Depending on how you are using this, and how long you want it to take, you may want to set a timer. Once your students get used to the format, this is a nice activity for the last 10 or 15 minutes of class to review (and solidify) learning. It can also be very interesting as the teacher to collect the cards and read the questions yourself afterwards. These questions indicate what your students thought were the most important points of the lesson. The questions can lead you to misconceptions that you need to address, or they can help you plan your lessons to better show students what is important and what is nice-to-know-but-not-so-important about the material you are teaching. If you are concerned about appropriateness of the questions, you could ask students to write the questions the day before so that you can collect and approve them overnight. Then do the interactive activity the next day.
I have used Quiz-Quiz-Trade with students in review lessons, and with teachers in workshops, and it is always a resounding success. I've seen students write "extra-credit" questions on the back of the card. I once had someone write an essay question to which she expected a developed oral response (this was a teacher in one of my workshops). Hopefully you will have success (and fun) with it also!
(Disclaimer: I didn't invent this activity - I read about it somewhere years ago, but for the life of me I can't figure out where I first found it. It was probably in a strategy book of some sort with a title like 101 Strategies for _________. I've perused my personal library looking for it, and it just doesn't seem to be in any of the strategy books that I own. If you know where it came from, please let me know so that I can credit that source.)