Before the exercise, ask students to recall sources of light. Use this worksheet to explain that the brighter the light source, the more space it can light up. Identify the different light sources in the pictures, then check the brighter light source in each pair. The biggest natural source of light is the sun.
Earth is a habitable planet for humans and all life forms, providing us with what we need to survive. However, erosion caused by air, water or man can destroy or crumble parts of its surface. Teach kids the three causes of erosion and help them circle the correct one on a worksheet.