When Khan Academy adds new content to a subject, it may cause the percent of your mastery to go down because of the newly added material that you have yet to mastered. If the material is familiar to you, you can start earning back your percentage points quickly though Mastery Challenges.

Check the Help Center to see if the recent changes could have affected your mastery percentage!

**Update (August 15, 2016):**

The Math mission is changing! You can find out more in **this article**.

**Update (October 26, 2015):**

**Algebra 2 "Radical equations and functions"**

Brand new exercises:

- Solve square-root equations (basic)
- Solve square-root equations (advanced)

Exercises that were removed:

- Radical equations

**Update (October 23, 2015):**

**Algebra 2 "Polynomial expressions, equations, and functions"**

Brand new exercises:

- Find the zeros of polynomials
- Determine the end behavior of polynomials
- Determine whether a polynomial function is even or odd from its formula

Exercises that were removed:

- Advanced structure in expressions
- Solutions of quadratic equations
- The fundamental theorem of algebra
- Graphs of polynomials

Existing exercises there were added from other topics:

- Factor quadratics with a leading coefficient of 1
- Factor quadratics with a leading coefficient other than 1
- Factor polynomials using quadratic methods
- Factor polynomials with quadratic forms
- Factor simple special products
- Factor differences of squares
- Factor perfect squares
- Factor polynomials with special product forms
- Determine whether a function is even or odd from its graph

**Update (October 22, 2015):**

**Algebra 1 "Quadratic equations and functions"**

Brand new exercises:

- Solve quadratic equations by using structure
- Determine the number of solutions of a quadratic equation
- Identify and use the different forms of quadratic functions
- Compare properties of quadratic functions
- Graph quadratic functions in factored form

Exercises that were removed:

- Vertex of a parabola

**Update (October 8, 2015):**

**3rd grade multiplication and division**

We added ~20 new exercises that help students practice basic multiplication and division facts.

**Update (October 6, 2015):**

**5th-grade place value**

Brand new exercises:

- Decimal place values
- Value of a decimal digit
- Multiplying and dividing decimals by 10
- Multiplying and dividing whole numbers by 10, 100, and 1000
- Multiplying and dividing decimals by 10, 100, and 1000
- Decimals in written form
- Comparing decimals challenge
- Rounding decimals using a number line

And most of the existing place value exercises underwent significant improvements

**Update (September 28, 2015):**

**3rd-grade multiplication and division**

Brand new exercises:

- Multiplying with visuals
- Dividing with visuals
- Letters and symbols in multiplication and division equations
- Multiplying by 0 or 1
- Dividing by 1
- Commutative property of multiplication
- Associative property of multiplication
- Distributive property of multiplication

**Update (September 15, 2015):**

**Algebra 2 "Rational expressions, equations, and functions" topic**

Brand new exercises:

- Solve equations with one rational expression (advanced)
- Solve equations with two rational expressions
- Determine the end behavior of rational functions
- Identify and analyze discontinuities of rational functions

New exercises from other topics:

- Least common multiple

Exercises that were removed:

- Dividing polynomials by binomials 1
- Dividing polynomials by binomials 2
- Dividing polynomials by binomials 3
- Simplifying rational expressions 4
- Multiplying and dividing rational expressions 4
- Multiplying and dividing rational expressions 5
- Adding and subtracting rational expressions 1
- Adding and subtracting rational expressions 3
- Adding and subtracting rational expressions 7
- Extraneous solutions to rational equations

The rest of the exercises in this topic were edited.

**Update (September 10, 2015):**

**7th-grade geometry**

New:

- Area and circumference of parts of circles
- Shaded areas
- Identifying supplementary, complementary, and vertical angles
- Finding missing angles
- Triangle inequality theorem

**Update (September 10, 2015):**

**Algebra 2**

*A NEW topic was added! Say hello to "Arithmetic with polynomials"*

Brand new exercises:

- Divide polynomials by monomials
- Divide polynomials by linear binomials

Exercises that were edited:

- Divide polynomials by polynomials
- Use the Polynomial Remainder Theorem to analyze factors of polynomials

**Update (September 6, 2015):**

**Algebra 1**

*A NEW topic was added! Say hello to "Introduction to exponential functions"*

Brand new exercises:

- Construct basic exponential functions from the initial value and the common ratio
- Construct basic exponential functions from a table or a graph
- Graphs of basic exponential functions
- Interpret formulas of basic exponential functions
- Interpret graphs and tables of basic exponential functions

New exercises that were added from Algebra 2:

- Distinguish between linear and exponential models
- Compare end behavior of polynomial and exponential functions

**Update (September 1, 2015):**

**Algebra 2**

*A NEW topic was added! Say hello to "Manipulating functions"*

New exercises:

- Evaluate composite functions from formulas
- Evaluate composite functions from graphs and tables
- Compose functions
- Shift functions

Removed exercises:

- Evaluating composite functions

Modified exercises:

- Model situations by combining functions using arithmetic operations
- Model situations by composing functions
- Find inverse values of functions
- Find inverses of polynomial, radical, and rational functions
- Verify that two functions are inverses
- Analyze invertible and non-invertible functions

**Update (August 31, 2015):**

**4th grade place value**

New exercises:

- Place value blocks
- Creating largest or smallest number
- Multiplying and dividing by 10
- Writing numbers in expanded form
- Writing numbers in written form
- Comparing multi-digit numbers
- Rounding whole numbers 2

Modified exercises:

- Place value introduction
- Understanding place value
- Understanding whole number representations
- Rounding whole numbers

**Update (August 20, 2015):**

**Geometry's "Transformations" topic**

New exercises:

- Perform dilations
- Find the dilation that maps a given figure to another (basic)
- Find the dilation that maps a given figure to another (advanced)

**Update (August 19, 2015):**

**Algebra 1**

*The topic "Exponent expressions and equations" was replaced by the topic "Expressions with rational exponents and radicals." The tutorial "Radical equations" was moved to Algebra 2.*

New exercises:

- Single-step simplification of radical expressions

**Update (August 4, 2015):**

**3rd-grade rounding**

New exercises:

- Rounding to the nearest 10 or 100 on the number line
- Rounding challenge

**Update (July 29, 2015):**

**6th-grade stats**

New exercises:

- Effects of shifting, adding, and removing a data point
- Comparing data displays

**Update (July 12, 2015):**

**Early math and 3rd grade**

New exercises:

- Select strategies for adding within 100
- Adding and subtracting within 1000 using a number line
- Find the missing number (addition and subtraction within 1000)

**Update (June 26, 2015):**

**Early math**

New exercises:

- Adding 1s or 10s
- Subtracting 1s or 10s
- Breaking apart two-digit addition problems
- Regrouping: two-digit number plus one-digit number
- Regrouping: two-digit number minus one-digit number
- Find the missing number (addition and subtraction within 100)
- Breaking apart three-digit addition problems

**Update (June 17, 2015):**

**Algebra 1**

*"Multiplying and factoring expressions" was renamed to "Introduction to polynomials and quadratic factorization."*

New exercises:

- Adding and subtracting polynomials with two variables
- Multiplying monomials by monomials
- Multiplying monomials by polynomials
- Finding special products of binomials (advanced)
- Factors and divisibility
- Factoring monomials
- Factoring polynomials by taking a common factor
- Factoring perfect squares

Exercises that were removed:

- Factoring algebraic expressions using the distributive property

Existing exercises that were added to the topic:

- Greatest common factor

**Update (June 10, 2015):**

**Algebra 2**

Removed the "Partial fraction expansion" tutorial

Added the "Direct and inverse variation" tutorial

**Precalculus**

Added the "Partial fraction expansion" tutorial

**Algebra 1**

Removed the "Ratios and proportions" topic, except for "Rational and irrational numbers"

**Update (June 2, 2015):**

__7th-grade rates and proportional relationships__

New exercises:

- Identifying proportional relationships with graphs
- Writing proportional equations
- Interpreting graphs of proportional relationships

Renamed exercises:

- Rate problems with fractions (old name: Rate problems 1)
- Identifying proportional relationships (old name: Analyzing and identifying proportional relationships
- Solving proportions (old name: Proportions 1)
- Proportion word problems (old name: Constructing proportions to solve application word problems)

Removed exercises:

- Rate problems 2 (not needed in 7th grade)
- Constructing and comparing proportional relationships (deemed poor student experience)

**Update (May 28, 2015):**

**Two variable linear-inequalities**

New exercises:

- Checking solutions to two-variable linear inequalities
- Checking solutions to systems of inequalities
- System of inequalities word problems

All of the existing linear inequalities exercises were moved from the "Systems of equations" topic to this new topic.

**Update (May 19, 2015):**

**5th-grade fractions**

New exercises:

- Understanding fractions as division word problems
- Dividing fractions by whole numbers introduction
- Dividing whole numbers by unit fractions introduction

**Update (May 18, 2015):**

**6th-grade ratios, rates, and percentages**

Added these exercises:

- Comparing rates
- Converting between fractions and percents

**Update (May 13, 2015):**

**7th-grade expressions, equations, and inequalities (formerly "variables and expressions")**

Added these exercises:

- Factoring with the distributive property
- Equivalent expressions with negative numbers and the distributive property
- Two-step equations with decimals and fractions
- Find the mistake in solving two-step equations

**Update (May 3, 2015):**

**Algebra 1, Introduction to Algebra**

Added an exercise:

- Units

**Update (Apr 30, 2015):**

**Early math place value**

Removed exercises:

- Teen numbers 2
- Teen numbers 3

**Update (Apr 29, 2015):**

**4th-grade fractions**

New Exercises:

- Comparing decimals and fractions

- Comparing decimals visually

- Fraction-decimal intuition

- Understanding place value for decimals greater than one

- Decimals in words

- Decimals intuition with grids

Renamed exercises:

Fractions as division by 10 or 100 --> Rewriting fractions as decimals

Converting decimals to fractions 1 --> Rewriting decimals as fractions

**Update (Apr 27, 2015):**

**4th-grade fractions**

New exercises:

- Different wholes

- Adding and subtracting mixed numbers with like denominators 2

- Multiplying fractions and whole numbers intuition

- Multiplying unit fractions and whole numbers

- Equivalent fractions with denominators of 10 and 100 intuition

- Equivalent fractions with denominators of 10 and 100

- Decompose fractions with denominators of 100

Name changes:

- Equivalent fractions introduction --> Equivalent fractions introduction (Exercise overhauled. Simplified items so it's a more appropriate introductory exercise. Will be running tests to evaluate the design of these items.)

- Understanding multiplying fractions and whole numbers --> Multiplying Fractions and Whole Numbers: Equivalent Expressions

**Update (Apr 24, 2015):**

__6th-grade variables, expressions, equations, and inequalities__

New:

- Powers of fractions

- Evaluating expressions in two variables 2 (includes rational numbers)

- Expression value intuition

- Writing expressions with variables 1

- Distribute property with variables

- Combining like terms with distribution

- One-step equations with addition and subtraction 2

- One-step multiplication and division equations 2

- Find the mistake in solving one-step equations

- Testing solutions of inequalities

Removed exercises (beyond grade level):

- Writing expressions with exponents

- Evaluating exponent expression word problems

- Writing expressions with exponents word problems

**Update (Apr 22, 2015):**

__6th-grade arithmetic operations__

Removed exercises (but they still exist in 5th grade):

- Division by 2 digits

- Dividing completely

- Dividing fractions by whole numbers

- Dividing whole numbers by fractions

- Division with fractions and whole numbers word problems

- Understanding dividing fractions by fractions

- Dividing fractions by fractions and whole numbers applications

**Update (Apr 21, 2015):**

__4th-grade fractions__

New exercises:

- Different wholes

- Visually comparing fractions 2

**Algebra 1 Sequences (NEW TOPIC) / Precalculus Sequences**

New exercises:

- Evaluating sequences in recursive form

- Explicit formulas for arithmetic sequences

- Recursive formulas for arithmetic sequences

- Recursive formulas for geometric sequences

Existing exercises that are new to Algebra 1:

- Evaluating arithmetic sequences

- Evaluating geometric sequences

- Explicit formulas for geometric sequences

- Modeling with sequences

**Algebra 1 Systems of equations**

New exercise:

- Checking solutions to systems of equations

Removed exercises:

- Systems with one, zero, or infinite solutions

- Systems of equations word problems

**Algebra 1 Functions**

New exercise:

- Matching inputs to function outputs

**Update (Apr 18, 2015):**

**Algebra 1 Two-variable linear equations and introduction to functions**

Completely new exercises that were added:

- Intercepts from a table
- Interpreting linear tables word problems

Existing exercises that were added to the topic:

- Evaluating function expressions
- Interpreting function notation in context

**Update (Apr 15, 2015):**

**Algebra 1 Functions**

Exercises added:

- Interpreting function notation in context
- Domain of algebraic functions
- Domain of modeling functions
- Evaluating piecewise functions
- Domain and range of piecewise functions
- Recognizing maxima and minima
- Increasing and decreasing intervals
- Average rate of change word problems

Exercises relocated to other topics/missions:

- Interpreting graphs of linear and nonlinear functions
- Domain of a function
- Range of a function
- Direct and inverse variation
- New operator definitions 1
- New operator definitions 2
- Understanding linear and exponential models
- Modeling with one-variable equations and inequalities

**Update (Mar 26, 2015):**

**3rd grade fractions**

Exercises added:

- That's not fair!
- Writing fractions as whole numbers
- Visually comparing fractions

**Update (Mar 25, 2015):**

**8th-grade numbers and operations**

Exercises added:

- Equations with square and cube roots
- Square and cube roots of decimals and fractions
- More square and cube root problems
- Classifying numbers
- Approximating square roots
- Approximating irrational numbers without a calculator
- Approximating with orders of magnitude
- Adding and subtracting in scientific notation

Exercises removed from 8th grade:

- Converting decimals to fractions 2
- Whole number exponents with integer bases 2

**Update (Mar 20, 2015):**

**7th-grade negative numbers**

Exercises added:

- Dividing mixed numbers
- Exponents with negative fractional bases

**Update (Mar 3, 2015):**

**7th-grade negative numbers**

One exercise added: "Multiplying and dividing negative numbers: word problems".

**Update (Feb 26, 2015):**

**6th and 7th grade combining like terms**

Renamed and removed old "Combining like terms" exercise from 6th grade. It had negative coefficients inappropriate for 6th grade. It now exists only in 7th grade and is named "Combining like terms with negative coefficients".

Added new "Combining like terms" exercise to 6th grade that's limited to positive coefficients.

**Update (Feb 17, 2015):**

**7th Grade Mission **

*Note that exercise names are followed by unique URL identifiers in parenthesis. While the names of exercises may change, these identifiers will not.*

15 exercises were added:

- Signs of sums (signs-of-sums)
- Integer addition and subtraction: find the missing value (integer-addition-and-subtraction)
- Adding negative numbers on the number line (adding-negative-numbers-on-the-number-line)
- Integer addition and subtraction: equations and number lines (negative-number-addition-and-subtraction--equations-and-number-lines)
- Negative number addition and subtraction: interpretation problems (negative-number-addition-and-subtraction--interpretation-problems)
- Absolute value to find distance (absolute-value-to-find-distance)
- Integer addition and subtraction (integer-addition-and-subtraction-2)
- Negative number addition and subtraction: equivalent expressions (negative-number-addition-and-subtraction-equivalent-expressions)
- Negative signs in numerators and denominators (negative-signs-in-numerators-and-denominators)
- Sign rules for multiplication and division (sign-rules-for-multiplication-and-division)
- Properties of multiplication with negative numbers (properties-of-multiplication-with-negative-numbers)
- Complex fractions (complex-fractions)
- Comparing rational numbers (comparing-rational-numbers)
- Identifying whole, integer, and rational numbers (identifying-whole--integer--and-rational-numbers)
- Making inferences from sample items (making-inferences-from-random-samples)

9 exercises were updated:

- Adding negative numbers (adding_negative_numbers)
- Subtracting negative numbers (adding_and_subtracting_negative_numbers)
- Integer addition and subtraction: number line interpretation (understanding-addition-and-subtraction-on-the-number-line)
- Negative number addition and subtraction: word problems (adding-negative-numbers-word-problems)
- Absolute value to find distance 2 (constructing-and-interpreting-absolute-value)
- Understanding negative number addition and subtraction with variables: challenge problems (understanding-addition-and-subtraction-with-negative-numbers)
- Whole number exponents with integer bases (exponents_1.5)
- Divide by zero (dividing-integers)
- Signs of products and quotients (multiply-and-divide-rational-numbers)

1 exercise was removed:

- Operations with rational numbers (operations-with-rational-numbers)

**Update (Feb 9, 2015):**

**3rd Grade Mission **

5 exercises were added:

- Creating bar charts
- Reading bar charts 1
- Reading bar charts 2
- Reading pictographs 1
- Reading pictographs 2

**6th Grade Mission **

7 exercises were added:

- Rational numbers on the number line
- Number opposites 2
- Ordering rational numbers
- Comparing absolute values 2
- Points on the coordinate plane
- Graphing points and naming quadrants
- Distance between points on the coordinate plane

Also, Interpreting absolute value and Sorting absolute value word problems were merged into one exercise

**Geometry Mission **

11 new transformations exercises were added:

- Performing translations
- Performing rotations
- Performing reflections
- Defining translations (interactive)
- Translations
- Defining rotations (interactive)
- Rotations 1
- Rotations 2
- Defining reflections (interactive)
- Reflections 1
- Reflections 2

5 exercises were removed:

- Quantitatively defining rigid transformations
- Transforming polygons
- Performing transformations on the coordinate plane
- Translations of polygons
- Rotations of polygons

**Algebra I Mission**

28 skills were removed in the "Two-variable linear equations and introduction to functions" topic:

- 10 skills were coordinate plane or rates/proportional relationships exercises that appear in earlier grades
- 6 of them are now (or were already) in the "Analytic geometry" tutorial in geometry
- 12 were actual algebra exercises removed in favor of replacing them with a newer, better set (13 new skills)

- Constructing linear functions word problems
- Writing the equation of a line in any form
- Slope-intercept equation from two points
- Writing function rules from equations
- Graphing linear functions word problems
- Graphing solutions to two-variable linear equations
- Slope from a graph
- Slope from an equation in slope-intercept form
- Graph from slope-intercept equation
- Slope from two points
- Slope from an equation in standard form
- Graph from a standard form equation
- Slope-intercept equation from a graph

**Update (Jan 9, 2015):**

On or about Jan 9, 2015, two skills were removed from the Geometry mission.

**Update (Dec 29, 2014):**

On or about Dec 29, 2014, additions were made to the 3rd, 6th, 7th, and 8th-grade missions.

1 skill was added to 3rd grade:

- Comparing fractions with the same numerator or denominator

1 skill was added to 6th grade:

- Surface area

2 skills were added to 7th grade:

- Writing fractions as repeating decimals
- Rate problems 2

1 skill was added to 8th grade:

- Interpreting linear relationships

**Update (Dec 12, 2014):**

On or about Dec 12, 2014, the 6th-grade mission was modified.

17 skills were added:

- Calculating the interquartile range (IQR)
- Calculating the mean
- Calculating the mean absolute deviation (MAD)
- Calculating the mean from various data displays
- Calculating the median
- Calculating the median from data displays
- "Clusters, gaps, peaks, and outliers"
- Creating box plots 2
- Creating dot plots
- Creating frequency tables
- Creating histograms
- Data set warm-up
- Find a missing value given the mean
- Interpreting quartiles
- Median and range puzzlers
- Reading histograms
- Shape of distributions

3 were removed:

- Comparing the center and spread of data distributions
- Describing the shape of data distributions
- Understanding the mean

**Update (Sept 27, 2014):**

On or about Sept 23, 2014 there were new skills added to Fourth Grade (1 skill), Fifth Grade (2 skills), Sixth Grade (2 skills), and Seventh Grade (2 skills). Additionally, the PreAlgebra Mission no longer shows Mission Foundations. For review of material before PreAlgebra, consider the Arithmetic Mission.

**Update (Sept 18, 2014):**

On or about Sept 18, 2014, there were new skills added to Third Grade (1 skill), Fourth Grade (2 skills), Fifth Grade (4 skills), Sixth Grade (2 skills), and Pre-Algebra (1 skill).

**Update (Sept 13, 2014):**

On or about Sept 12, 2014, approximately 4 new skills were added resulting in a minor drop in percentages for low-level missions. Our volunteer found drops in percentages in Early Math, 3rd Grade, and 4th Grade.

**Update (Aug 25, 2014):**

Over the last weekend, some skills shifted Mission. This could result in changes of percentage Mastered. Check your skills for your particular mission to see if you've had a change in level, rather than rely on the percentage to indicate losing skills. Many of the skills which have been removed from Missions are lower level Mission Foundation skills, so users who mastered a large percentage of the skills that have been moved will see a reduction in percentage completed.

*See also:*