# Course Updates for Arithmetic in July 2021

We are excited to share that we've made significant enhancements to our **Arithmetic** course. One consequence of adding this new content is that it may impact learners’ Mastery percentages.

When we add new content and remove old content, Mastery percentages often change because the **number of available skills changes**. For example, if you mastered 90 out of 100 skills in a course, and we added 10 new skills, your mastery skill count would then be 90 out of 110. This change would change your Mastery percentage from 90% to 82%.

With this specific course update, we expect that Mastery percentages will change by a maximum of **54%**. Most people will see a much smaller Mastery percentage change.

You can see exactly what content items we’ve added and removed below. Happy learning!

**Content Added**

*Articles*

*Exercises*

*Videos*

Addition & subtraction: find the missing value (part 1 of 2) |

Addition & subtraction: find the missing value (part 2 of 2) |

Introduction to division with partial quotients (no remainder) |

**Content Removed**

*Articles*

Absolute value review |

Dividing decimals |

Dividing fractions review |

Equivalent fractions review |

Multiplying fractions review |

Number opposites |

Number opposites review |

Ordering negative numbers |

*Exercises*

2-step addition word problems within 100 |

2-step subtraction word problems within 100 |

Absolute value to find distance |

Add & subtract within 20 |

Add 2-digit numbers by making tens |

Add and subtract on the number line word problems |

Add and subtract within 20 word problems |

Add on a number line |

Add within 100 using a number line |

Add within 100 using place value blocks |

Add within 1000 |

Add within 20 |

Add within 20 visually |

Add within 5 |

Adding & subtracting decimals word problems |

Adding & subtracting negative numbers |

Adding decimals: hundredths |

Adding decimals: tenths |

Adding decimals: thousandths |

Adding up to four 2-digit numbers |

Adding up to four 2-digit numbers word problems |

Adding with arrays |

Addition word problems within 100 |

Array word problems |

Break apart 2-digit addition problems |

Break apart 3-digit addition problems |

Break apart 3-digit subtraction problems |

Compare and order absolute values |

Compare decimal place value |

Compare decimals (tenths and hundredths) |

Compare decimals through thousandths |

Compare fractions and mixed numbers |

Compare fractions on the number line |

Compare fractions using benchmark |

Compare fractions with different numerators and denominators |

Compare fractions with the same numerator or denominator |

Compare fractions word problems |

Converting fractions to decimals |

Create division equations with area models |

Decimals in words |

Decimals in written and expanded form |

Decimals on the number line: hundredths |

Decimals on the number line: tenths |

Dividing decimals 1 |

Dividing decimals 2 |

Dividing decimals: hundredths |

Dividing decimals: thousandths |

Dividing fractions word problems |

Dividing whole numbers like 56÷35 to get a decimal |

Division in contexts |

Division with arrays |

Equal groups |

Find missing divisors and dividends (1-digit division) |

Fraction and whole number division in contexts |

Fractions in contexts |

Multi-digit division |

Multiplication in contexts |

Multiply 1-digit numbers by 10, 100, and 1000 |

Multiply by 1-digit numbers with standard algorithm |

Multiply by tens |

Multiply fractions and whole numbers with fraction models |

Multiply using partial products |

Multiply whole numbers by 0.1 and 0.01 |

Multiply without regrouping |

Multiplying decimals like 0.847x3.54 (standard algorithm) |

Multiplying decimals like 2.45x3.6 (standard algorithm) |

Multiplying decimals like 4x0.6 (standard algorithm) |

Number opposites |

Order decimals |

Order decimals and fractions in different forms |

Order fractions |

Ordering negative numbers |

Relate decimals and fractions in words |

Relate fraction division to fraction multiplication |

Relate number lines to fraction bars |

Represent fraction multiplication with visuals |

Rewriting decimals as fractions challenge |

Round decimals |

Round decimals challenge |

Round decimals using a number line |

Select strategies for adding within 100 |

Select strategies for adding within 1000 |

Select strategies for subtracting within 1000 |

Signs of expressions |

Simplify fractions |

Subtract on a number line |

Subtract within 100 using a number line |

Subtract within 100 using place value blocks |

Subtract within 1000 |

Subtract within 20 |

Subtract within 20 visually |

Subtract within 5 |

Subtracting decimals: hundredths |

Subtracting decimals: tenths |

Subtracting decimals: thousandths |

Subtraction word problems within 100 |

Understand multiplication using groups of objects |

Unit fractions on the number line |

Write common fractions as decimals |

Write decimals and fractions shown on number lines |

Write decimals as fractions |

*Videos*

Absolute value as distance between numbers |

Adding & subtracting decimals word problem |

Adding 2-digit numbers without regrouping |

Adding 3-digit numbers |

Adding 53+17 by making a group of 10 |

Adding 7 + 6 |

Adding 8 + 7 |

Adding and subtracting on number line word problems |

Adding by making a group of 10 |

Adding decimals word problem |

Adding decimals: 0.822+5.65 |

Adding decimals: 9.087+15.31 |

Adding four two digit numbers |

Adding fractions with unlike denominators |

Adding mixed numbers with like denominators |

Adding multiple 2-digit numbers word problems |

Adding three decimals |

Adding two digit numbers on a number line |

Adding with arrays |

Adding with regrouping |

Adding within 20 using place value blocks |

Adding within 20 using ten frames |

Addition and subtraction with number lines |

Addition and subtraction word problems: gorillas |

Addition and subtraction word problems: superheroes |

Addition word problem: horses |

Basic addition |

Basic subtraction |

Breaking apart 2-digit addition problems |

Breaking apart 3-digit addition problems |

Comparing absolute values |

Comparing and ordering fractions |

Comparing decimals 2 |

Comparing decimals 3 |

Comparing decimals in different representations |

Comparing decimals: 156.378 and 156.348 |

Comparing decimals: 9.97 and 9.798 |

Comparing fractions |

Comparing fractions 2 (unlike denominators) |

Comparing fractions with > and < symbols |

Comparing fractions with like numerators and denominators |

Comparing improper fractions and mixed numbers |

Converting decimals to fractions 2 (ex 1) |

Converting decimals to fractions 2 (ex 2) |

Decimal place value |

Decimals as words |

Dividing by a multi-digit decimal |

Dividing decimals completely |

Dividing decimals with hundredths |

Dividing whole numbers & fractions: t-shirts |

Division in context |

Equal groups |

Expressing decimals in multiple forms |

Fraction to decimal: 11/25 |

Fraction word problem: lizard |

Graphing hundredths from 0 to 0.1 |

Graphing tenths from 0 to 1 |

Identifying hundredths on a number line |

Identifying tenths on a number line |

Identifying unit fractions word problem |

Intro to long division (no remainders) |

Intro to multiplying 2 fractions |

Intro to multiplying decimals |

Intro to remainders |

Long division with decimals |

Long division: 280÷5 |

Methods for subtracting 3-digit numbers |

Missing number for 3-digit subtraction within 1000 |

More ways to multiply |

Multi step addition word problem |

Multi-digit division strategies for decimals |

Multi-step subtraction word problem |

Multiplication in real world contexts |

Multiplying 2-digit by 1-digit |

Multiplying 3-digit by 1-digit |

Multiplying 4-digit by 1-digit (regrouping) |

Multiplying by multiples of 10 |

Multiplying challenging decimals |

Multiplying decimals: place value |

Multiplying multi-digit numbers |

Multiplying with distributive property |

Number opposites |

Ordering decimals |

Ordering decimals 1 |

Ordering decimals 2 |

Ordering decimals through thousandths |

Ordering fractions |

Ordering negative numbers |

Placing absolute values on the number line |

Plotting decimal numbers on a number line |

Relating decimals and fractions in words |

Repeated addition: haircuts |

Rewriting decimals as fractions: 0.15 |

Rewriting decimals as fractions: 0.36 |

Rewriting decimals as fractions: 0.8 |

Rounding decimals on the number line |

Strategies for adding 2-digit numbers |

Strategies for dividing by tenths |

Subtract within 20 using a number line |

Subtract within 20 using place value blocks |

Subtract within 20 using ten frames |

Subtracting 10s using place value |

Subtracting 14 - 6 |

Subtracting 1s using place value |

Subtracting 2-digit numbers without regrouping 1 |

Subtracting decimals: 39.1 - 0.794 |

Subtracting decimals: 9.005 - 3.6 |

Subtracting fractions with unlike denominators |

Subtracting in your head (no regrouping) |

Subtracting mixed numbers with like denominators |

Subtracting two-digit numbers without regrouping |

Subtracting with regrouping (borrowing) |

Subtraction by breaking apart |

Subtraction word problem: basketball |

Subtraction word problem: crayons |

Subtraction word problem: snow |

Subtraction word problem: tennis balls |

The idea of division |

Three digit addition word problems |

Three digit subtraction word problems |

Understanding place value when adding ones |

Understanding place value when adding tens |

Using arrays in word problems |

Using place value to add 3-digit numbers: part 2 |

Visualizing equivalent fractions |

Worked example: Converting a fraction (7/8) to a decimal |

Worked example: Rounding decimals to nearest tenth |

Worked example: Subtracting 3-digit numbers (regrouping from 0) |

Worked example: Subtracting 3-digit numbers (regrouping twice) |

Worked example: Subtracting 3-digit numbers (regrouping) |

Writing decimal numbers shown in grids |