If you're like me and terrible at thinking on your feet, it's best to come prepared even for the simple stuff. Use these questions to review what you've learned through Unit 7 of Let's Try! 2 (fourth grade).
How are you today?
How is the weather today?
What day is it today?
What day is tomorrow?
Do you like~ ? (cats, dogs, sports, games, fruit, vegetables, Mondays, books, movies, rain, fish, snow, pizza, chocolate)
What time is it?
How old are you?
What _______ do you like? (sports, fruit, vegetable, color, animal, weather, candy)
Do you have a~ ? (bike, hat, umbrella, mask, baseball, dog, cat, PC, pencil, ruler, eraser)
I recommend dividing the class into teams and having the students from alternating teams answer questions. When they answer correctly, give them points or the chance to get points (a Typhoon-style game works well with this format*). You could also just have students roll dice for points.
*Search 'esl typhoon game' and you should be able to find explanations from various ESL teachers about how to organize and play it.