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Mathematics

Addition & Subtraction

45 lessons · topologically ordered (prerequisites first).

  1. 1
    Subtraction as taking away or separating
    Ages 4–6 · high
  2. 2
    Addition as combining or putting together two
    Ages 4–6 · high
  3. 4
    Mentally adding hundreds to 3-digit numbers
    Ages 7–8 · med
  4. 5
    Mentally adding tens to 3-digit numbers
    Ages 7–8 · med
  5. 6
    Adding and subtracting tens mentally
    Ages 6–7 · med
  6. 7
    Subtracting multiples of 10
    Ages 6–7 · med
    • Subtraction as taking away or separating (hard)
  7. 8
    Reading +, −, and = symbols
    Ages 5–6 · high
    • Addition as combining or putting together two (hard)
    • Subtraction as taking away or separating (hard)
  8. 9
    Numbers up to 10 into pairs
    Ages 4–6 · high
    • Addition as combining or putting together two (hard)
  9. 10
    Fluent adding and subtracting within 5
    Ages 5–6 · high
    • Addition as combining or putting together two (hard)
    • Subtraction as taking away or separating (hard)
  10. 11
    Addition in any order
    Ages 6–7 · high
    • Addition as combining or putting together two (hard)
  11. 12
    Finding a missing number in addition
    Ages 6–7 · high
    • Addition as combining or putting together two (hard)
    • Subtraction as taking away or separating (hard)
  12. 13
    Representing Addition and Subtraction
    Ages 4–6 · high
    • Addition as combining or putting together two (hard)
    • Subtraction as taking away or separating (hard)
  13. 14
    Addition and subtraction strategies
    Ages 6–7 · low
    • Addition as combining or putting together two (hard)
    • Subtraction as taking away or separating (hard)
  14. 15
    What the equals sign means
    Ages 6–7 · high
  15. 16
    Number bonds to 9
    Ages 4–6 · high
    • Numbers up to 10 into pairs (hard)
  16. 17
    Grouping numbers to add
    Ages 6–7 · low
    • Addition as combining or putting together two (hard)
    • Addition in any order (hard)
  17. 18
    Inverse: addition undoes subtraction
    Ages 6–7 · high
    • Finding a missing number in addition (hard)
  18. 19
    Addition and subtraction word problems
    Ages 4–6 · high
    • Representing Addition and Subtraction (hard)
  19. 20
    Fluent adding and subtracting within 10
    Ages 6–7 · high
    • Number bonds to 9 (hard)
    • Fluent adding and subtracting within 5 (hard)
  20. 21
    Number bonds
    Ages 5–6 · high
    • Number bonds to 9 (hard)
    • Fluent adding and subtracting within 5 (hard)
  21. 22
    Adding Three Small Numbers
    Ages 6–7 · med
    • Number bonds to 9 (soft)
    • Grouping numbers to add (hard)
  22. 23
    Unknown in Addition & Subtraction
    Ages 6–7 · med
    • Inverse: addition undoes subtraction (soft)
    • What the equals sign means (hard)
  23. 24
    Addition and subtraction within 20
    Ages 6–7 · high
    • Number bonds to 9 (hard)
    • Fluent adding and subtracting within 10 (hard)
  24. 25
    Adding and subtracting
    Ages 5–6 · high
    • Number bonds (hard)
  25. 26
    Adding within 100
    Ages 6–7 · high
    • Addition and subtraction within 20 (hard)
  26. 27
    Fluent adding and subtracting within 20
    Ages 7–8 · high
    • Addition and subtraction within 20 (hard)
    • Fluent adding and subtracting within 10 (hard)
  27. 28
    Fluent addition and subtraction
    Ages 6–7 · med
    • Addition and subtraction within 20 (hard)
  28. 29
    Early Word Problems
    Ages 5–7 · high
    • Adding and subtracting (hard)
    • Addition and subtraction word problems (soft)
  29. 30
    Mental addition and subtraction (age 6+)
    Ages 6–7 · med
    • Adding and subtracting (hard)
  30. 31
    Fluent adding and subtracting within 100
    Ages 7–8 · high
    • Adding within 100 (hard)
    • Fluent adding and subtracting within 20 (hard)
  31. 32
    Adding two two-digit numbers
    Ages 6–7 · med
    • Mental addition and subtraction (age 6+) (hard)
    • Adding and subtracting tens mentally (hard)
  32. 33
    Addition and subtraction within 1000
    Ages 7–8 · high
    • Fluent adding and subtracting within 100 (hard)
  33. 34
    Two-Step Word Problems
    Ages 7–8 · high
    • Fluent adding and subtracting within 100 (hard)
    • Early Word Problems (hard)
  34. 35
    Addition and subtraction strategies (age 7+)
    Ages 7–8 · high
    • Fluent adding and subtracting within 100 (hard)
  35. 36
    Numbers on a number line
    Ages 7–8 · med
    • Fluent adding and subtracting within 100 (soft)
  36. 37
    Mental addition and subtraction (age 7+)
    Ages 7–8 · med
    • Fluent adding and subtracting within 100 (soft)
  37. 38
    Adding numbers
    Ages 7–8 · med
    • Fluent adding and subtracting within 100 (hard)
    • Adding Three Small Numbers (hard)
  38. 39
    Mental and written addition and subtraction
    Ages 6–7 · med
    • Adding two two-digit numbers (hard)
    • Early Word Problems (soft)
  39. 40
    Adding and subtracting (age 7+)
    Ages 7–8 · high
    • Fluent adding and subtracting within 100 (hard)
    • Addition and subtraction within 1000 (hard)
  40. 41
    Estimating by rounding
    Ages 7–9 · high
    • Inverse: addition undoes subtraction (hard)
    • Addition and subtraction within 1000 (soft)
  41. 43
    Missing number problems (age 7+)
    Ages 7–8 · high
    • Adding and subtracting (age 7+) (soft)
    • Two-Step Word Problems (hard)
  42. 44
    Adding and subtracting (age 8+)
    Ages 8–9 · med
    • Adding and subtracting (age 7+) (hard)
  43. 45
    Fluent adding and subtracting within 1000
    Ages 8–9 · med
    • Addition and subtraction within 1000 (hard)
    • Adding and subtracting (age 7+) (hard)
  44. 47
    Two-step addition and subtraction problems
    Ages 8–9 · med
    • Adding and subtracting (age 8+) (hard)
    • Missing number problems (age 7+) (hard)
  45. 49
    Two-Step Equations
    Ages 8–9 · high
    • Fluent adding and subtracting within 1000 (soft)
    • Two-Step Word Problems (hard)