Calculating the necessary energy to recycle aluminum from aluminum oxide which was a question on the 2015 AP Chemistry exam. [6:16]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

2018 report from the U.S. Department of State which discusses Pakistan's poor human rights practices.

The 2018 report on human rights practices in Spain includes information on topics of concern related to human rights such as government corruption; violence against women, children, persons with disabilities, and national/racial/ethnic minorities; and the rights of workers. Briefly mentions the status of conditions in Spain related to the minority Basque population and the separatist ETA group.

New activities designed specifically for the 2019-2020 school year spotlight the 2020 Census and the importance of making sure everyone is counted, especially children. The decennial count impacts the federal funds that communities receive for special education, classroom technology, teacher training, after-school programs, school lunch assistance, and more. PreK-grade 12.

This problem helps students practice adding three numbers whose sum are 20 or less.

"High-Rise" is the final book in a quartet of novels by J.G. Ballard. Read an overview and view additional resources such as articles and collection items.

'The Waste Land' is a long poem by the American writer T.S Eliot. Read an overview and view additional resources such as articles, collection items, and teacher resources.

'Their Lonely Betters' is a short, four-stanza lyric poem by W.H. Auden. Read an overview and view additional resources such as articles, collection items, and teacher resources.

Written by Caryl Churchill in 1982, "Top Girls" was one of the first plays to engage directly with Thatcherism. Read an overview of "Top Girls" and view additional resources such as articles, collection items, and videos.

Learn to write a narrative essay by identifying the differences between descriptive and narrative essays, knowing the difference between autobiographical and biographical narratives, recognizing the structure of narratives, and identifying and stressing the importance of personal growth in a narrative essay.

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Hear about different models of 21st century learning skills from experts in the education field. Chris Rush from New Classrooms, Teresa Napoli from School of One and Rebecca Rufo-Tepper from the Institute of Play discuss the emergence of new approaches to learning, such as personalized and game-based learning. [5:37]

This section investigates the process for dividing rational expressions that are written as fractions. Additionally, it provides opportunities to explore different processes for simplifying rational expressions written as fractions prior to dividing.

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This section explores the process for adding and subtracting rational expressions. It primarily focuses on how to identify and use the Least Common Denominator to combine fractions with rational expressions.

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This short video and interactive assessment activity is designed to give fifth graders an overview of 24-hour clocks.

This short video and interactive assessment activity is designed to give fourth graders an overview of 24-hour clocks.

This section builds from previous sections on simplifying, multiplying, dividing, adding, and subtracting rational expressions, and it investigates how to apply those skills to solving rational equations. It also covers several approaches to checking the solutions to confirm that they are correct or to determine if any are extraneous solutions.

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Discover these exciting 25 activities that develop reading and writing skills while having fun. The activities are split for two different age groups.

This section draws on previous sections that explored how to add, subtract, multiply, and divide rational numbers in order to solve real-world problems involving rational equations. It explores how to apply these procedures in order to solve equations.

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This section explores the process for solving radical equations, including those with square, third, and fourth roots. It also investigates how, when, and why some solutions that appear to be correct are incorrect, and are therefore considered extraneous solutions.

A free CK-12 account is required to view all materials.