Try Sun and Seasons Lab free in your browser, with nothing to install and no account. Stand a stick in a schoolyard in your own town and watch its shadow through the day and the year. See the Sun climb high in summer and stay low in winter, and the day stretch from 9 hours to 15. Then test the idea that summer comes when Earth is closer to the Sun: Earth is closest in January. Measure a real shadow and check it against the app.