259K views · 638 reactions | These free, student-friendly videos will be the perfect addition to your science lessons where kids can learn about the northern lights and much more! Subscribe to our YouTube channel for more!   | McGraw Hill PreK-12 | Facebook

19 reactions | Genetic drift happens when chance events cause alleles to spike or decline from one generation to the next. Sometimes a segment of a population gets isolated and continues to grow and mutate on it's own. Sometimes populations change as a result of natural disasters or human intervention. https://youtu.be/mFvmY9JASO4 | CrashCourse | Facebook