Choosing a question is sometimes difficult. Start by thinking about what interests you. What have you always wanted to know about this topic? Then narrow your focus. The internet can provide information on all kinds of topics.
What's your thing? I bet you enjoy sports. Sports are all about physics. Maybe your into how things grow or how to keep the earth green. That is the science of ecology. Keep thinking...Brainstorming is MY game.
Lab assistants, help your researcher focus on one topic. The huge amount of information and choices can make websites difficult to manage. An organized researcher is invaluable. Curiosity is what moves science forward. What are you curious about?
Although discovering the 'right' question can be difficult, it is not impossible. Choose a topic that interests you, choose a question that has a yes or no answer, ask your teachers or your trusty lab assistants for help. All questions are worth investigating.