We've done a few examples together where we were faced with 1 variable. Why not try one that has 2 variables? Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-expressions-and-variables/cc-6th-substitution/e/evaluating_expressions_2?utm_source=YT&utm_medium=Desc&utm_campaign=6thgrade Watch the next lesson: https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-expressions-and-variables/cc-6th-evaluating-expressions/v/variables-and-expressions-1?utm_source=YT&utm_medium=Desc&utm_campaign=6thgrade Missed the previous lesson? https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-negative-number-topic/cc-6th-coordinate-plane/v/coordinate-plane-word-problems-exercise?utm_source=YT&utm_medium=Desc&utm_campaign=6thgrade Grade 6th on Khan Academy: By the 6th grade, you're becoming a sophisticated mathemagician. You'll be able to add, subtract, multiply, and divide any non-negative numbers (including decimals and fractions) that any grumpy ogre throws at you. Mind-blowing ideas like exponents (you saw these briefly in the 5th grade), ratios, percents, negative numbers, and variable expressions will start being in your comfort zone. Most importantly, the algebraic side of mathematics is a whole new kind of fun! And if that is not enough, we are going to continue with our understanding of ideas like the coordinate plane (from 5th grade) and area while beginning to derive meaning from data! (Content was selected for this grade level based on a typical curriculum in the United States.) ... https://www.youtube.com/watch?v=S_OX3ByvBSc Note: All Khan Academy content is available for free at (www.khanacademy.org)

Introduction to the ellipse. Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algebra2/conics_precalc/ellipses-precalc/e/equation_of_an_ellipse?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraII Watch the next lesson: https://www.khanacademy.org/math/algebra2/conics_precalc/ellipses-precalc/v/foci-of-an-ellipse?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraII Missed the previous lesson? https://www.khanacademy.org/math/algebra2/conics_precalc/circles-tutorial-precalc/v/completing-the-square-to-write-equation-in-standard-form-of-a-circle?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraII ... https://www.youtube.com/watch?v=lvAYFUIEpFI Note: All Khan Academy content is available for free at (www.khanacademy.org)

Naming benzene derivatives introduction. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/science/organic-chemistry/aromatic-compounds/naming-aromatic/v/naming-benzene-derivatives?utm_source=YT&utm_medium=Desc&utm_campaign=organicchemistry Organic Chemistry on Khan Academy: Carbon can form covalent bonds with itself and other elements to create a mind-boggling array of structures. In organic chemistry, we will learn about the reactions chemists use to synthesize crazy carbon based structures, as well as the analytical methods to characterize them. We will also think about how those reactions are occurring on a molecular level with reaction mechanisms. Simply put, organic chemistry is like building with molecular Legos. Let's make some beautiful organic molecules! 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. For free. For everyone. Forever. #YouCanLearnAnything ... https://www.youtube.com/watch?v=A5r7wkwDID4 Note: All Khan Academy content is available for free at (www.khanacademy.org)

Introduction to molecular and empirical formulas. Calculating molecular mass. More free lessons at: http://www.khanacademy.org/video?v=gfBcM3uvWfs ... https://www.youtube.com/watch?v=gfBcM3uvWfs Note: All Khan Academy content is available for free at (www.khanacademy.org)