- (5 min) Mental Math
- What is 30% of 90? [27]
- What is one half of one tenth? [1/20]
- Take the number of days in a leap year and add four [370]
- What is 3 cubed divided by 3 squared? [3]
- Take the number of meters in a kilometer and subtract the number of centimeters in a meter. [900]

- (5 min) Review order of operations for evaluations and
multiplications. Do from left to right

- If parentheses, do operations within parenthesis first
- Do exponents and square roots from left to right
- Multiply and divide from left to right
- Add and subtract from left to right

Evaluate the following with class help on each step. Go around the room one at a time and ask each student to calculate one step. Stress rewriting at each step.

Demonstrate substitution: for a = 2, b = 4, c = 6; (a b + c)^{2}= 196

Review multiplication of positive and negative numbers: First do the multiplication, then figure out the sign. If there are an*even*number of negative signs, then the answer is*positive*. If there are an*odd*number of negative signs, then the answer is*negative*.

What is (- 1)^{2}? What is (- 1)^{3}? What is (- 1)^{4}? What is (- 1)^{15}?

- (10 min) Adding and subtracting positive and negative numbers

All addition and subtraction starts from zero on a number line. You move right for positive and left for negative. If there is no sign to start with, then you assume it is positive and move right.

---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 <------------------------ ---------------> - 6 + 4 = - 2

Here's another way to think about it if the student is good at following rules. This works for some kids.

If the signs are the same, add and use the sign (+ or -) that both numbers have.

If the signs are different, subtract and use the sign of the larger one for the answer.

To subtract a negative number, combine the signs like in multiplying, and then add: 3 - (-4) = + 7

- (Remainder of class) In-class exercise

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