Lesson Plan # 13 - Order of operations, Solving
equations:
- (5 min) Mental Math
- Start with 77, add 23, then divide by 10 [10]
- How many inches are there in 4 feet? [48]
- Multiply 3.6 by 10 [36]
- What is 1/2 times 3/4? [3/8]
- What is the decimal for 86 divided by 10? [8.6]
- (5 min) Review of homework #12 (<= 3 problems)
- (5 min) Discuss order of operations:
- Pass out the "Order of Operations" handout.
Follow the discussion in the handout. Go through the
examples on the handout.
- Do these examples
(ask students what operations to do
first):
- 3 + 4 x 6 - 9 = [18]
- ( 3 + 4 ) x 6 - 9 = [33]
- 8 + 6 / 2 + 4 = [15]
- ( 8 + 6 ) / 2 + 4 = [11]
- (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
- Do these examples:
- 6 - x = 2 Ask:"six minus what number gives you 2?"[x =4]
- x + 15 = 25 Ask:"what number plus 15 is 25?"[x = 10]
- 4x = 8 Ask:"4 times what number is 8?"[x = 2]
- x/3 = 3 Ask:"what number divided by 3 is 3?"[x = 9]
- 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.
|