3rd grade math on Khan Academy: We know you've been rocking through 2nd grade adding and subtracting all kinds of whole numbers (up to 2 digits, right?). That's awesome! In 3rd grade math we want you to start using bigger numbers and start multiplying and dividing, too. By the way, did you know that some numbers aren’t actually “whole?” They’re “partially whole.” We call them fractions! We want you to start playing around and having fun with those, too. There's also area, perimeter, and place value to be discovered. Whew. We have so much to do and can't wait to do it with you. Let's go!
Sal does an example problem to determine the size and direction of the magnetic force on a proton moving through a magnetic field. Created by Sal Khan.
Watch the next lesson: https://www.khanacademy.org/science/physics/magnetic-forces-and-magnetic-fields/magnets-magnetic/v/magnetism-4?utm_source=YT&utm_medium=Desc&utm_campaign=physics
Missed the previous lesson? https://www.khanacademy.org/science/physics/magnetic-forces-and-magnetic-fields/magnets-magnetic/v/cross-product-2?utm_source=YT&utm_medium=Desc&utm_campaign=physics
Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
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.
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https://www.youtube.com/watch?v=LTuGQy4rmmo
Note: All Khan Academy content is available for free at (www.khanacademy.org)
If verb tense allows you to control the past, the present, and the future, then aspect gives you even finer control over time. David, Khan Academy's resident grammarian, explains.
Practice this yourself on Khan Academy right now: https://www.khanacademy.org/humanities/grammar/partsofspeech/grammar-verbs/e/simple-verb-aspect?utm_source=YT&utm_medium=Desc&utm_campaign=grammar
Watch the next lesson: https://www.khanacademy.org/humanities/grammar/partsofspeech/grammar-verbs/v/simple-aspect?utm_source=YT&utm_medium=Desc&utm_campaign=grammar
Missed the previous lesson? https://www.khanacademy.org/humanities/grammar/partsofspeech/grammar-verbs/v/the-truly-irregular-irregular-verbs-the-parts-of-speech-grammar?utm_source=YT&utm_medium=Desc&utm_campaign=grammar
Grammar on Khan Academy: Grammar is the collection of rules and conventions that make languages go. This section is about Standard American English, but there's something here for everyone.
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https://www.youtube.com/watch?v=r7Psg-4vvsA
Note: All Khan Academy content is available for free at (www.khanacademy.org)
Moving easily between gallons, quarts, pints, cups, and fluid ounces makes you really valuable in a ton of different situations.
Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-measurement-topic/cc-4th-unit-conversion/e/measurement-units?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-unit-conversion/v/converting-weight?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-metric-distance?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.)
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https://www.youtube.com/watch?v=9UVgO8zS474
Note: All Khan Academy content is available for free at (www.khanacademy.org)
Decompose an irregular shape to find area of entire figure.
Watch the next lesson: https://www.khanacademy.org/math/pre-algebra/measurement/perimeter/v/introduction-to-perimeter?utm_source=YT&utm_medium=Desc&utm_campaign=PreAlgebra
Missed the previous lesson? https://www.khanacademy.org/math/pre-algebra/measurement/area-basics/v/comparing-areas-of-plots-of-land?utm_source=YT&utm_medium=Desc&utm_campaign=PreAlgebra
Pre-Algebra on Khan Academy: No way, this isn't your run of the mill arithmetic. This is Pre-algebra. You're about to play with the professionals. Think of pre-algebra as a runway. You're the airplane and algebra is your sunny vacation destination. Without the runway you're not going anywhere. Seriously, the foundation for all higher mathematics is laid with many of the concepts that we will introduce to you here: negative numbers, absolute value, factors, multiples, decimals, and fractions to name a few. So buckle up and move your seat into the upright position. We're about to take off!
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.
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https://www.youtube.com/watch?v=xo4VpX2IIMk
Note: All Khan Academy content is available for free at (www.khanacademy.org)
Exploring the actual weightings for the CPI-U basket of goods
More free lessons at: http://www.khanacademy.org/video?v=-JTw7gNwT6Y
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https://www.youtube.com/watch?v=-JTw7gNwT6Y
Note: All Khan Academy content is available for free at (www.khanacademy.org)
2X2 matrices can define transformations for the entire plane. In this worked example, we see how to find a single matrix that defines the same transformation as the composition of two other matrices.
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https://www.youtube.com/watch?v=OzoEqs1f1S8
Note: All Khan Academy content is available for free at (www.khanacademy.org)
Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/early-math/cc-early-math-add-sub-100/cc-early-math-making-groups-of-ten/e/making-100?utm_source=YT&utm_medium=Desc&utm_campaign=EarlyMath
Watch the next lesson: https://www.khanacademy.org/math/early-math/cc-early-math-add-sub-100/cc-early-math-sub-ones-tens/v/understanding-place-value-while-subtracting-ones?utm_source=YT&utm_medium=Desc&utm_campaign=EarlyMath
Missed the previous lesson?
https://www.khanacademy.org/math/early-math/cc-early-math-add-sub-100/cc-early-math-making-groups-of-ten/v/addition-using-groups-of-10-intro?utm_source=YT&utm_medium=Desc&utm_campaign=EarlyMath
Early Math on Khan Academy: Math begins with counting. It's the most important skill we learn in our early years and becomes the foundation for all other math concepts. Once we can count, we can add, subtract, and measure the world around us. Shortly thereafter, we can learn about place values, plots, graphs, time, money, and shapes. These early math skills are presented in this subject's tutorials in a straightforward, understandable, and (dare we say it) fun way!
Want a virtual coach for Early Math? Unlock the Early Math mission on Khan Academy here: https://www.khanacademy.org?utm_source=YT&utm_medium=Desc&utm_campaign=EarlyMath
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https://www.youtube.com/watch?v=DzJvR56Suss
Note: All Khan Academy content is available for free at (www.khanacademy.org)
AP free response question experimentally estimating the resistivity of a conductive dough.
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https://www.youtube.com/watch?v=AOntr8OksEY
Note: All Khan Academy content is available for free at (www.khanacademy.org)
David and Paige, KA’s resident grammarians, introduce a new piece of punctuation: the apostrophe!
Practice this yourself on Khan Academy right now: https://www.khanacademy.org/the-comma/e/introduction-to-the-apostrophe
Watch the next lesson: https://www.khanacademy.org/humanities/grammar/punctuation/the-apostrophe/v/introduction-to-contractions-the-apostrophe-punctuation-khan-academy
Punctuation on Khan Academy: Punctuation is the collection of squiggles, dots, and lines that we use to separate sentences and their parts. Is a question mark punctuation? Yes, and so is an exclamation point!
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.
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https://www.youtube.com/watch?v=o6zzLAhEyqo
Note: All Khan Academy content is available for free at (www.khanacademy.org)