4

Ngorongoro Crater, Tanzania

3

Vasco da Gama

3

Meteorites, Meteoroids, and Meteors

4

Maddy's Idaho Diary

3

Mercury

3

Mars

4

Mount Fuji, Japan

4

Maddy's Arizona Diary

3

The Moon

4

Chip's Tips on Kenya

4

Maddy's Oregon Diary

4

Chip's Tips on Chile

4

Serengeti, Tanzania

3

Neil Armstrong

3

The Earth

2

Solar System

3

Asteroids