| Roanoke Colony |
|
3.2 |
|
|
| Robert L. Johnson |
|
7.8 |
|
|
| Roberto Clemente |
|
6.6 |
|
|
| Robotics Engineer |
|
6.5 |
|
|
| Robots |
|
6.3 |
|
|
| Robot Scientist |
|
5.8 |
|
|
| Robot Scientist |
|
5.7 |
|
|
| Rock Climbing |
|
5.8 |
|
|
| Rocket League: Beginner's Guide |
|
|
|
|
| Rocks |
|
|
|
|
| Rocks and Minerals |
|
4.8 |
|
|
| Rogue Planets |
|
3.3 |
|
|
| Roller Coasters |
|
2.9 |
|
|
| Rosa Parks: The Making of a Myth |
|
|
|
|
| Rosie's Brain |
New!
|
|
|
|
| Roswell |
|
3.6 |
|
|
| Rosy Wolf Snails Invade Pacific Islands |
|
4.0 |
|
|
| Rotary Clubs |
|
5.3 |
|
|
| Roving the Red Planet |
|
|
|
|
| Ruby-Throated Hummingbird Migration |
|
3.7 |
|
|
