3

The Earth

4

Earthquakes

4

Mount Fuji, Japan

3

Straits of the World

3

Caves of the World

3

Isaac Newton

3

Bays of the World

2

Four Seasons! Deciduous Forest

3

Houses from around the World

3

Canyons of the World

4

Hurricanes

2

Evergreen Forests! Taiga

3

Neptune

4

Desert

3

Lunar Eclipse

2

Treeless Plains! Steppe

4

Montane Forest

3

Charles Darwin

3

Harbors of the World

4

Volcanoes

2

Warm Grasslands! Savanna

3

Venus

3

Sinkholes of the World

3

Senses

3

Wetlands of the World

3

Continents of the World

3

Constellations

3

Galaxies

2

Hot and Dry! Desert

3

Archipelagos of the World