1.
Lesson Plan on Ratio
Prepared by Gliceryl Mae Manlangit
Target Students: Grade Five
Subject Matter: Mathematics
EDUC 190
A. Motivation
Show a photo of Leonardo da Vinci’s Golden Ratio.
This is a picture of Leonardo da Vinci’s Golden Ratio. The golden ratio is
based on Fibonacci’s numbers where every number in the sequence is the
sum of the previous two numbers. The golden ratio is 1. 618 033. In this
photo, each succeeding finger bone is 1. 618 the length of the preceding
finger bone. The distance from elbow to wrist is 1.618 the distance from
wrist to fingertip.
It is also said that from the top of the head to the belly button is measured
as one, while the measurement from the belly button to the bottom of the
feet is 1.618.
http://www.flickr.com/photos/hawkexpress/500696658/
2.
http://www.flickr.com/photos/uhuru1701/2249290466/
B. Objectives
To define ratios
To express ratios in colon notation, in fraction, and in English
expression
To find out ratios of word problems
To identify body ratios
C. Review of Prior Learning
Ask the students about the process of multiplying fractions.
Ask for volunteers to multiply these fractions:
2 × 5 3 × 6
6 8 4 8
3.
D. Information and Examples
Show a bowl of marbles with red, blue and green colors. How many green
marbles are here in the bowl? How many red marbles are there? (Write
their answers on the board.) What do you think is the relationship between
the green marbles and the red marbles? This relationship is called ratio.
Ratios- can be expressed in colon notation (:); in English expression
(____ is to ___); or in fraction form (3 ripe mangoes/6 mangoes)
Ratio can be defined as:
Part to whole sense- ratio of the number of parts compared to the number of the whole e.g
4 red marbles is to 6 marbles
http://www.flickr.com/photos/turtles-r-us/2280480323/
Part to part sense- describes relationship between two subsets of the same set e.g. 7 blue
yo-yos is to 8 green yo-yos
Relationship between two independent sets- describes relationship between two sets that
are unrelated e.g. 2 milk cartons is to 8 cookies
5.
Ratio as a rate- can describe pricing information e.g. 1 candy is to P1; or can also
describe rate e.g. 50 miles per hour
http://farm4.static.flickr.com/3140/3065142930_efe7a79774.jpg
Reminder:
Ratios in fraction form should always be labeled to avoid confusion.
Ratios in fraction form may also have 0 as denominator.
E. Practice and Feedback
Problem solving on ratio
In a bag of red and green sweets, the ratio of red sweets to green sweets is
3:4. If the bag contains 120 green sweets, how many red sweets are there?
Solution:
Assign variables :
Let x = red sweets
Write the items in the ratio as a fraction.
6.
Step 2: Solve the equation
Cross Multiply
3 × 120 = 4 × x
360 = 4x
Isolate variable x
Answer: There are 90 red sweets.
http://www.onlinemathlearning.com/ratio-problems.html
F. Application and Summary
Body Ratios
Instructions:
Look for a partner.
Cut a string equal to the length of the height of your partner.
Answer the following questions:
1. How many of one of your feet equals to your height?
2. How many of one of our wrist circumference equals to your waist?
3. How many of your waist equals to your height?
4. How many of your ring finger equals to your neck circumference?
After the activity, the teacher will ask the students to go back to their proper
places.
Generalization
What are ratios? Expected Response: Ratios describe the relationship between
parts to whole, parts to parts, and between two independent sets.
How are ratios expressed? ER: Ratios can be written using a colon notation, using
English expression, and through fractions
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