4

Ngorongoro Crater, Tanzania

3

Mercury

3

Asteroids

4

Chip's Tips on Chile

4

Mount Fuji, Japan

4

Chip's Tips on Kenya

4

Maddy's Idaho Diary

3

The Earth

2

Solar System

4

Maddy's Oregon Diary

3

The Moon

4

Serengeti, Tanzania

4

Maddy's Arizona Diary

3

Mars

3

Meteorites, Meteoroids, and Meteors

3

Vasco da Gama

3

Neil Armstrong