4

Ngorongoro Crater, Tanzania

3

The Moon

3

Asteroids

4

Maddy's Oregon Diary

4

Serengeti, Tanzania

3

Mercury

4

Mount Fuji, Japan

3

Neil Armstrong

4

Chip's Tips on Kenya

2

Solar System

3

The Earth

4

Maddy's Idaho Diary

4

Maddy's Arizona Diary

3

Meteorites, Meteoroids, and Meteors

3

Mars

4

Chip's Tips on Chile

3

Vasco da Gama