Number: all 211 lessons, free

Arithmetic

92 lessons

The four operations on whole numbers and decimals, and the rules they obey.

1.1Arithmetic

1.2Adding and subtracting within 20

1.3Adding within five and tenKindergarten

1.4Addition and subtraction

1.5Addition as putting togetherKindergarten

1.6Parts, wholes and number bondsKindergarten

1.7Subtraction as taking awayKindergarten

1.8Subtracting within tenKindergarten

1.9Acting out add and take-away stories within 10Kindergarten

1.10Finding the missing number in an equationGrade 1

1.11Subtraction as an unknown addendGrade 1

1.12Adding two-digit numbers without regroupingGrade 1

1.13Doubles and near doublesGrade 1

1.14Fact familiesGrade 1

1.15Properties of additionGrade 1

1.16Subtraction as the differenceGrade 1

1.17Ten more and ten lessGrade 1

1.18Counting on to add and counting back to subtractGrade 1

1.19Making ten and bridging through tenGrade 1

1.20Problems with the start, change or result missingGrade 1

1.21Problems with the total missingGrade 1

1.22Subtracting multiples of tenGrade 1

1.23Adding a one-digit number to a two-digit number by making a tenGrade 1

1.24Arrays: rows and columns of objectsGrade 2

1.25Multi-digit addition

1.26Multiplication and division

1.27Adding on an open number lineGrade 2

1.28Addition and subtraction problems in words

1.29How many more and how many fewerGrade 2

1.30Multi-digit subtraction

1.31Problems with the starting amount missingGrade 2

1.32Regrouping in additionGrade 2

1.33Subtracting two-digit numbers without regroupingGrade 2

1.34Two-step addition and subtraction problemsGrade 2

1.35What multiplication meansGrade 2

1.36Adding and subtracting within 20 from memoryGrade 2

1.37Bar models for story problemsGrade 2

1.38Estimation and mental math

1.39Mental strategies

1.40Subtracting three-digit numbers by place value, including across zeroGrade 2

1.41The standard subtraction algorithmGrade 4

1.42The partial sums methodGrade 2

1.43ArraysGrade 3

1.44Counting up to find a differenceGrade 3

1.45Facts for two, five and tenGrade 3

1.46Multiplication facts

1.47Patterns in the multiplication tableGrade 3

1.48Regrouping in subtractionGrade 2

1.49The distributive propertyGrade 3

1.50What division meansGrade 3

1.51Compensation when adding and subtractingGrade 3

1.52Division factsGrade 3

1.53Estimating sums and differencesGrade 3

1.54Facts for three, four and sixGrade 3

1.55Properties of multiplicationGrade 3

1.56Equal group problemsGrade 3

1.57Estimating by roundingGrade 4

1.58Facts for seven, eight and nineGrade 3

1.59Multiplication and division undo each otherGrade 3

1.60Problems using several operationsGrade 3

1.61The standard addition algorithmGrade 4

1.62Times as manyGrade 4

1.63Adding and subtracting decimalsGrade 5

1.64Multi-digit multiplication

1.65Remainders and what they meanGrade 4

1.66Doubling, halving and quick productsGrade 4

1.67Long division

1.68Multiplying by tens and hundredsGrade 4

1.69Subtracting across zerosGrade 4

1.70The area modelGrade 3

1.71Dividing by a single digitGrade 4

1.72Friendly numbers and deliberate over and under estimatesGrade 5

1.73Partial productsGrade 4

1.74Partial quotientsGrade 4

1.75Decimal arithmetic

1.76Numerical expressionsGrade 5

1.77Order of operations

1.78Grouping symbolsGrade 5

1.79Writing and reading numerical expressions from wordsGrade 5

1.80Multiplying decimalsGrade 5

1.81The standard long division algorithmGrade 5

1.82The standard multiplication algorithmGrade 5

1.83Dividing by a two-digit numberGrade 5

1.84Dividing decimalsGrade 5

1.85Where the point goes in a productGrade 5

1.86Dividing by a decimalGrade 5

1.87Order of operations with powersMath 6

1.88Multiplying multi-digit decimals with the standard algorithmMath 6

1.89Decimal problems in wordsMath 6

1.90Dividing multi-digit decimals with the standard algorithmMath 6

1.91Order of operations with negative numbersMath 7

1.92Estimating a huge quantity from small factsAlgebra 1

Counting and cardinality

29 lessons

Numbers name how many. Counting is matching things to number words, one each.

2.1Comparing numbers and the symbols >, < and =Grade 1

2.2Counting a set of objectsKindergarten

2.3Counting and cardinality

2.4One-to-one correspondenceKindergarten

2.5Saying the counting words to 20Kindergarten

2.6Subitizing and ten framesKindergarten

2.7Comparing quantitiesKindergarten

2.8Counting to 100 and beyondKindergarten

2.9How counting tells how manyKindergarten

2.10Ten framesKindergarten

2.11Counting by tens to one hundredKindergarten

2.12Counting on and counting backKindergarten

2.13Counting out a given number of objectsKindergarten

2.14Number names, numerals and zeroKindergarten

2.15One more and one lessKindergarten

2.16Comparing two numbers to 10Kindergarten

2.17Ordinal numbersKindergarten

2.18Writing the numerals 0 to 10Kindergarten

2.19The equal sign means the same amountGrade 1

2.20Counting a large pile by groupingGrade 1

2.21Counting by twos, fives, threes and foursGrade 2

2.22Placing a number on a number lineGrade 1

2.23The number line

2.24Counting, reading and writing numbers to 120Grade 1

2.25Counting by hundredsGrade 2

2.26Counting past one hundredGrade 2

2.27Even and odd numbersGrade 2

2.28Skip counting

2.29Number lines with different scalesGrade 2

Place value

23 lessons

Where a digit sits decides what it is worth: ones, tens, hundreds.

3.1Place value

3.2Tally marks and Roman numeralsGrade 4

3.3Teen numbers as ten and some moreKindergarten

3.4Tens and onesGrade 1

3.5Base ten blocks and trading ten for oneGrade 2

3.6Reading and writing numbers to 1,000Grade 2

3.7Comparing and ordering whole numbersGrade 2

3.8The place value chartGrade 2

3.9Expanded formGrade 2

3.10Rounding

3.11Rounding to the nearest ten or hundredGrade 3

3.12Decimal place value

3.13Numbers to one millionGrade 4

3.14Tenths and hundredthsGrade 4

3.15Comparing and ordering decimalsGrade 4

3.16Decimals on a number lineGrade 4

3.17Rounding to any place, including decimalsGrade 4

3.18Multiplying and dividing by ten, one hundred and one thousandGrade 4

3.19Numbers in other basesGrade 5

3.20Rounding decimalsGrade 5

3.21Thousandths: reading, writing and expanded formGrade 5

3.22Dividing a decimal by ten, one hundred or one thousandGrade 5

3.23Multiplying a decimal by ten, one hundred or one thousandGrade 5

Divisibility and primes

14 lessons

How whole numbers break into factors.

4.1Divisibility and primes

4.2Factors and multiplesGrade 4

4.3Divisibility rulesGrade 4

4.4Listing multiplesGrade 4

4.5Prime and composite numbersGrade 4

4.6Prime factorizationMath 6

4.7Tests for three and nineMath 6

4.8Greatest common factor and least common multiple

4.9Greatest common factor by listingMath 6

4.10Least common multiple by listingGrade 4

4.11Perfect, abundant, deficient and amicable numbersMath 6

4.12The sieve of EratosthenesMath 6

4.13Finding them from prime factorizationsMath 6

4.14Every number has exactly one prime factorizationMath 6

Integers

9 lessons

Whole numbers and their negatives: the counting numbers extended both ways.

5.1Integers

5.2Negative numbersMath 6

5.3Opposites and zero pairsMath 6

5.4Placing and comparing integers on a number lineMath 6

5.5Absolute valueMath 6

5.6Adding and subtracting integers

5.7Multiplying and dividing integersMath 7

5.8Adding integersMath 7

5.9Subtracting integersMath 7

Exponents and roots

18 lessons

Repeated multiplication, and undoing it.

6.1Perfect squares and perfect cubesMath 6

6.2Powers of tenGrade 5

6.3Base, exponent and the value of a powerMath 6

6.4Exponent notation

6.5Exponents and roots

6.6Square rootsMath 8

6.7Laws of exponents

6.8Multiplying and dividing powers with the same baseMath 8

6.9Powers of powers, products and quotientsMath 8

6.10Scientific notation

6.11Square and cube roots

6.12Zero and negative exponentsMath 8

6.13Writing and reading scientific notationMath 8

6.14Calculating in scientific notationMath 8

6.15Comparing numbers in scientific notationMath 8

6.16Cube roots and higher rootsMath 8

6.17Rational exponentsAlgebra 2

6.18Higher rootsAlgebra 2

Rational numbers

11 lessons

Any number that can be written as one integer over another.

7.1Converting between fractions and decimalsGrade 5

7.2Negative fractions and decimals on the number lineMath 6

7.3Rational numbers

7.4Comparing and ordering rational numbersMath 6

7.5What makes a number rationalMath 7

7.6Operations with rational numbersMath 7

7.7Terminating and repeating decimalsMath 7

7.8Multiplying and dividing rational numbersMath 7

7.9Rational numbers in real situationsMath 7

7.10Which fractions give terminating decimalsMath 8

7.11Turning a repeating decimal into a fractionMath 8

Irrational and real numbers

9 lessons

Numbers that are not fractions, and the complete number line they fill in.

8.1Irrational and real numbers

8.2Irrational numbersMath 8

8.3Approximating irrational numbersMath 8

8.4Sorting a number into its setsMath 8

8.5The real number lineMath 8

8.6ClosureAlgebra 1

8.7Commutative, associative and distributive propertiesAlgebra 1

8.8Identity and inverse elementsAlgebra 1

8.9Properties of real numbers

Complex numbers

6 lessons

Numbers built from a square root of negative one.

9.1Adding, subtracting and multiplying complex numbersAlgebra 2

9.2Complex numbers

9.3Imaginary and complex numbersAlgebra 2

9.4Conjugates and dividing complex numbersAlgebra 2

9.5Complex roots come in pairsAlgebra 2

9.6The complex plane, modulus and argumentPrecalculus