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

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

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

- (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:
- a - bc for a = 10, b = 3, c = 2 [Answer: 4]

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

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

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

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

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

- (Remainder of class) In-class Exercise.

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