Mom asks you to be home by 5:45. You know the number of minutes it takes to get home. What time do you leave? Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-measurement-topic/cc-4th-time/e/measuring-time-word-problems?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Watch the next lesson: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-measurement-topic/cc-4th-time/v/time-word-problem?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Missed the previous lesson? https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-measurement-topic/cc-4th-unit-conversion/v/converting-weight?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Grade 4th on Khan Academy: 4th grade is the time to start really fine-tuning your arithmetic skills. Not only will you be a multi-digit addition and subtraction rockstar, but you'll extend the multiplication and division that you started in 3rd grade to several digits. You'll also discover that you sometimes have something left over (called a "remainder") when you divide. In 3rd grade you learned what a fraction is. Now you'll start adding, subtracting, multiplying, and comparing them. You'll also see how they relate to decimals. On other fronts, you'll learn how to convert between different units (which is super important when comparing the size and speed of robot unicorns in different countries) and continue your journey thinking about various shapes in two dimensions. Some of the foundational concepts of geometry (like lines, rays and angles) also get introduced. As always, we'll round this out with a healthy dose of applied word problems and explorations of number patterns and properties (including the ideas of factors, multiples and prime numbers). The fun must not stop! (Content was selected for this grade level based on a typical curriculum in the United States.) ... https://www.youtube.com/watch?v=kul2ZmVIQZk Note: All Khan Academy content is available for free at (www.khanacademy.org)

Many chemical reactions have mechanisms that consist of multiple elementary steps. The energy profile for a multistep reaction can be used to compare the activation energies of the different steps and identify the rate-determining step. The energy profile can also be used to determine the overall change in energy for the reaction. View more lessons or practice this subject at https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:kinetics/x2eef969c74e0d802:activation-energy-and-reaction-rate/v/multistep-reaction-energy-profiles 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://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc Volunteer here: https://www.khanacademy.org/contribute?utm_source=youtube&utm_medium=desc ... https://www.youtube.com/watch?v=l4VCiJulLKw Note: All Khan Academy content is available for free at (www.khanacademy.org)

Carbon as a building block of life. Watch the next lesson: https://www.khanacademy.org/science/biology/properties-of-carbon/carbon/v/silicon-based-life?utm_source=YT&utm_medium=Desc&utm_campaign=biology Missed the previous lesson? https://www.khanacademy.org/science/biology/water-acids-and-bases/acids-bases-and-ph/v/buffer-system?utm_source=YT&utm_medium=Desc&utm_campaign=biology Biology on Khan Academy: Life is beautiful! From atoms to cells, from genes to proteins, from populations to ecosystems, biology is the study of the fascinating and intricate systems that make life possible. Dive in to learn more about the many branches of biology and why they are exciting and important. Covers topics seen in a high school or first-year college biology course. About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. ... https://www.youtube.com/watch?v=JgYlogdtJDo Note: All Khan Academy content is available for free at (www.khanacademy.org)

Solubility intuition ... https://www.youtube.com/watch?v=ccDKr4TIWfk Note: All Khan Academy content is available for free at (www.khanacademy.org)