1. Significant Figures/Dimensional Analysis

2. Objective: Today I will be able to:
Apply significant figures to solving problems
Apply dimensional analysis to solving problems
Informal Assessment – monitoring student questions and interactions as they complete the practice problems
Formal assessment – analyzing student responses to the exit ticket and practice problems
Common Core Connection
Make sense of problems and persevere in solving

3. Lesson Sequence Evaluate: Warm-Up
Engage/Elaborate: Real life Dimensional Analysis Problems
Evaluate: Exit Ticket

4. Warm-Up
Solve and record your answer to the correct number of significant figures:
1) x 520 =
.0025 x 3.15 =
1, – =

5. Objective Today I will be able to:
Apply significant figures to solving problems
Apply dimensional analysis to solving problems

6. Homework Complete the dimensional analysis practice
Study for scientific notation quiz on Thursday, September 11

7. Agenda Warm-Up Dimensional Analysis Notes
Real Life Dimensional Analysis Practice Problems
Exit Ticket

8. Dimensional Analysis Notes

9. Conversion Factor 12 inches 1 foot 7 days 1 week ½
A Fraction that is equal to the number one
Two quantities that equal the same thing
12 inches
1 foot
7 days
1 week .5

10. Dimensional Analysis 1 dozen 12 eggs 12 eggs 1 dozen Yes!
Q: Do these two fractions equal the same quantity?
1 dozen
12 eggs
12 eggs
1 dozen
Yes!

11. Dimensional Analysis Problem Solving Tips
Read the problem
Write down what you are given, put it over 1
Write down what you are looking for
List all possible conversion factors for the problem
Make a road map
Solve the problem

12. Practice Problem 1 Q: How many minutes are there in 10 hours? 10 hours
1. Read the problem
2. Write down what you are given, put it over 1
3. Write down what you are looking for.
The number of minutes
x minutes
10 hours 1

13. Practice Problem 1 Cont 1 hour 60 minutes
4. List all possible conversion factors for the problem
-We know that one hour = 60 minutes
5. Make a road map
Hours ? Minutes
1 hour minutes
60 minutes hour

14. Practice Problem 1 Cont. 6. Solve the problem
We also know that when you multiply, if 2 quantities are placed in opposite corners of each other, they will cancel out
For example,
Incorrect, the units do not cancel out
10 hours hour = hours 2
minutes minutes

15. Practice Problem 1 cont. 10 hours . 60 minutes = 600 minutes 1 1 hour
7. Solve for Correct Answer!
10 hours minutes = minutes
hour

16. Practice Problem 2 Q: How many minutes are there in 12 weeks?
Weeks  Days  Hours  ? Minutes
12 weeks days hours . minutes =
week day hour
12 weeks . 7 days . 24 hours . 60 minutes =
week day 1 hour

17. = 1,048,320 minutes or 1,051,200 minutes (365 days)
Practice Problem 3
Q: How many minutes are there in 2 years?
Years  Weeks  Days  Hours  Minutes
2 years weeks days hours . minutes =
1 year week day hour
2 years . 52 weeks . 7 days . 24 hours . 60 minutes =
year week day hour
= 1,048,320 minutes or ,051,200 minutes (365 days)

18. Practice Problem 4 500 mL . 1 Liter = 0.500 L 1 1000 mL
Q: How many liters are in 500 mL? mL  ? L
500 mL Liter = L mL

19. Practice Problem 5 20 kg . 1000 g . 1000 mg = 2 x 107 mg 1 1 kg 1 g
Q: How many milligrams are there in 20 kg? kg  g  ? mg
20 kg g mg = 2 x 107 mg
kg g

20. Dimensional Analysis Practice
Complete the practice at your desk. Show all work. Write answer to correct number of sig figs.Will be collected

21. Exit Ticket
Why don’t you count significant figures in a conversion factor?
What do you base significant figures on in a dimensional analysis problem.
Solve the problem below. Show all work and round to the correct number of significant figures.
How many seconds are in the 7 hour school day?