Lesson Plan # 13 - Order of operations,
Solving equations:

  1. (5 min) Mental Math
    1. Start with 77, add 23, then divide by 10 [10]
    2. How many inches are there in 4 feet? [48]
    3. Multiply 3.6 by 10 [36]
    4. What is 1/2 times 3/4? [3/8]
    5. What is the decimal for 86 divided by 10? [8.6]

  2. (5 min) Review of homework #12 (<= 3 problems)

  3. (5 min) Discuss order of operations:

    1. Pass out the "Order of Operations" handout. Follow the discussion in the handout. Go through the examples on the handout.

    2. Do these examples
      (ask students what operations to do first):

      1. 3 + 4 x 6 - 9 = [18]

      2. ( 3 + 4 ) x 6 - 9 = [33]

      3. 8 + 6 / 2 + 4 = [15]

      4. ( 8 + 6 ) / 2 + 4 = [11]

  4. (10 min) Discuss equation solving. Follow the handout. Use this discussion:

    "Remember in the second grade when your teacher asked you to fill in the box in a problem like this:"

    4 + = 10

    "In algebra, all we do is use a letter, like 'x' instead of a box:"

    4 + X = 10

  5. Do these examples:

    1. 6 - x = 2 Ask:"six minus what number gives you 2?"[x =4]

    2. x + 15 = 25 Ask:"what number plus 15 is 25?"[x = 10]

    3. 4x = 8 Ask:"4 times what number is 8?"[x = 2]

    4. x/3 = 3 Ask:"what number divided by 3 is 3?"[x = 9]

  6. Show students how to solve problems that have 2 terms on one side, by covering up the term containing x, solving for the whole term, then finding x:

    Examples:
    Equation Step 1:
    Cover up
    boxed term
    Step 2:
    Solve for
    boxed term
    Step 3:
    Solve for value
    in box
    3x + 1 = 7 3x = 6, so
    x = 2
    x/2 - 1 = 3 - 1 = 3 x/2 = 4, so
    x = 8

  • (Remainder of class) In-class Exercise.

  • Hand out homework as students successfully complete the in-class exercise.