Start at the core and learn all of the Earth's layers and how they interact with the layers of the atmosphere.
Discover that Earth has many cycles: day and night, the seasons, the water cycle... and how we have a life cycle.
The Wind blows, clouds bring rain and snow, learn how it all works.
Describe the world around you by using the concepts heavy and light, big and little, long and short, etc.
Understanding life processes of plants and animals and their basic needs.