There are two variations of this activity. One is focused on speaking and I think would work best for higher level students, the other on writing.
For speaking-focus (approx 15 minutes):
Have the students make groups (up to six students per group), and pass out a deck of cards to each group.
Students will choose who will be the first to give a 'quiz.'
The first student pulls a card and has to then give hints (using the target grammar) about what is pictured.
This is a food that is round.
This is a food (which) many people in Osaka love.
This is a food which has octopus in it.
Answer: It's takoyaki.
The first person in the group to get the right answer receives the card as a point. That winner will then be the next quiz giver. Continue like that until out of cards or out of time.
Writing-focused version (can take most of the class period depending on your students' level):
Have one student from each group get a deck of picture cards and pass out the cards randomly to their group members, but don't let them make groups just yet. I had each student take 3 cards.
Give them time to write 2-3 hints for each of their cards on the worksheet, individually. Once students have finsihed making their quizzes, let them make groups and quiz each other. You can use the cards as point markers like in the speaking version.
I made this activity with relative pronouns in mind, but I think it's pretty flexible and can be used to practice many grammar points.