Q: How could you charge your phone using lemons as the energy source?
Q: How can you measure the size of a molecule?
Q: Can you estimate the minimum mass of graphene required to cover the entire surface of Earth?
Q: What is the only letter that does not appear in the periodic table?
Q: How do you make green fire?
Q: How can you make an invisible ink?
Teachers we want to hear from you too if you want to get involved and set some questions of your own – email firstname.lastname@example.org.