1. Representing Ratios as Concrete Models & Fractions Lesson 2 3 rd 6 Weeks TEKS 6.3B

2. Ratio  Comparison of 2 quantities  When forming a ratio it is very important to compare the correct numbers in the order the problem requires.  Represented with a model.

3. EX: The ratio 2 out of 5 can be represented with a model.

4. Written using a colon or as a fraction. EX: 2:5 or 5 2

5. Written as a decimal 52.0 0.4 10/7/2015 20- 0

6. Types of Ratios Compare part of something to the whole. (This is most like a regular fraction.) Compare one part to another part. Compare all of something to all of something else. (whole to whole)

7. Differences between ratios & fractions A fraction’s denominator always tells you how a whole is divided into parts. With ratios, a denominator may tell you: –How a whole is divided; or –The number of parts in another whole; or –A different part of the whole than the numerator describes (like the ratio of green marbles to red marbles in the same bag of marbles).

8. Ratios also do not follow fractions rules when it comes to units. –A fraction compares things that have the same units (like 5 pieces of pie compared to 12 pieces in a whole pie). –A ratio may compare things with like units or with unlike units (like 25 miles to one gallon).

9. Fractions can be added or subtracted. Ratios cannot be added or subtracted.

10. EX: 7 out of 10 boys ride a bike to school. Write this ratio as a decimal »7 to 10 7 10 0.7

11. EX: What is the ratio of shaded to unshaded? 16 to 14 We can simplify our answer. Divide 16 and 14 by 2. 8 to 7 What is the ratio of shaded to unshaded?