Scientists are naturally curious about the world. While many people may pass by a curious phenomenon without sparing much thought for it, a scientific mind will take note of it as something worth further thought and investigation
This step could also be called "research." It is the first stage in understanding the problem you have chosen. After you decide on your area of science and the specific question you want to ask, you will need to research everything that you can find about the problem. You can collect information on your science fair topic from your own experiences, books, the internet, or even smaller "unofficial" experiments. This initial research should play a big part in the science fair idea that you finally choose.
Let's take the example of the tomatoes in the garden. You like to garden and notice that some tomatoes are bigger than others and wonder why. Because of this personal experience and an interest in the problem, you decide to learn more about what makes plants grow.
For this stage of the Scientific Method, it's important to use as many sources as you can find. The more information you have on your science fair project topic, the better the design of your experiment is going to be, and the better your science fair project is going to be overall. Also try to get information from your teachers or librarians, or professionals who know something about your science fair topic. They can