Density (conceptual) | Middle school chemistry | Khan Academy

Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now!

Our new middle school chemistry course launches in July 2025, but we couldn’t wait to share it! Videos like this one are rolling out over the next few months to give you a sneak peek of what’s to come. 🧪💡

Want to explore more? Check out the full middle school playlist here:
https://www.youtube.com/playlist?list=PLSQl0a2vh4HBnhjPgsJU2y1UhMwcYmb5u

Density reveals how much mass is packed into a given volume. Different substances have different densities. Water’s density is 1.0 g/cm³, meaning any material with a density higher than this will sink in water, while lower densities float. Since each substance has a consistent density, this property helps identify materials and explain why some objects are “light” or “heavy” for their size.

00:00 A ton of bricks vs a ton of feathers
01:32 What is density?
04:18 Density values of common materials
04:45 Check your understanding of density
05:42 Water, floatation, & neutron stars
07:00 Summary

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Donate or volunteer today! Donate here: https://donate.khanacademy.org/give/419869/#!/donation/checkout

Volunteer here: https://www.khanacademy.org/contribute?utm_source=youtube&utm_medium=desc
...
https://www.youtube.com/watch?v=d7VPJ4DYwQQ
Note: All Khan Academy content is available for free at (www.khanacademy.org)