4

Ngorongoro Crater, Tanzania

4

Maddy's Idaho Diary

3

Asteroids

3

Vasco da Gama

4

Mount Fuji, Japan

2

Solar System

3

The Moon

3

Meteorites, Meteoroids, and Meteors

3

Mercury

4

Maddy's Oregon Diary

4

Chip's Tips on Chile

4

Serengeti, Tanzania

4

Maddy's Arizona Diary

4

Chip's Tips on Kenya

3

Mars

3

Neil Armstrong

3

The Earth