Lesson Plan # 11 - Beginning Algebra: variables, operators and expressions

  1. (5 min) Mental Math
    1. Start with 200, subtract 50, then divide by 10 [15]
    2. Multiply 80 by 30 then divide by 10 [240]
    3. Multiply 1/2 by 2/3, then reduce [1/3]
    4. How many feet are in 20 yards? [60]
    5. What is 1/3 times 1/3 times 1/3? [1/27]

  2. (5 min) Review of homework #10 (<= 3 problems)

  3. (10 min) Introduce variables, operators, and expressions: Pass out the "Variables, operators and expressions" handout and follow the discussion there. After the discussion, use these examples, asking students to come to the board to solve them:
    1. a - bc for a = 10, b = 3, c = 2 [Answer: 4]

    2. 3a - 2b for a = 4, b = 5 [Answer: 2]

    3. a/b for a = 30, b = 5 [Answer: 6]

    4. 4ab for a = 6, b = 2 [Answer: 48]

    5. 8b/a for a = 2, b = 3 [Answer: 12]

    6. a - b for a = 4, b = 8 [Answer: -4] <===negative answer!!!

  4. (Remainder of class) In-class Exercise.

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