The Nature Conservancy has some Nature Trivia quizzes that are fun. They're multiple choice and you can keep on guessing till you get the answer. The topics are water, the sun, plants, animals, birds, and the oceans. I think the level is maybe 4th grade to 8th grade.
This might be an activity a student and tutor could do together when homework is done. Each quiz takes just a short time. Again, something for when a student says "I don't feel like reading my book."
There's a cute video showing adults and children trying to answer questions: Why is the sky blue? Why is the grass green? Why do zebras have stripes?