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

When a warmer object meets a cooler one, energy flows until they reach the same temperature, also known as thermal equilibrium. This transfer of energy between systems is what we call heat. Temperature measures the average kinetic energy or motion of these particles. All matter contains moving particles with kinetic energy, which contributes to its thermal energy.

00:00 Intro
00:53 What is thermal energy?
02:27 What is temperature?
04:37 What is heat?
06:48 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