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This lesson idea reviews ratios
Title – Ratio
By – Jawa Mariappan
Primary Subject – Math
Secondary Subjects – Math
Grade Level – 6-7
Understand, write and use ratios.
The concept behind ratio is very simple. However, students seem to have serious difficulty, when they are in 8-9th grade, and they have to write ratios that involve variables to solve equations. Hence, special attention must be paid in 6-7th grades so that students clearly understand ratios.
I suggest not even use the word ratio till they grasp the meaning behind ratio. Ask them if they know how to compare things. All of them will say, yes.
Ask them questions such as:
How much pizza is left, if you eat half the pizza? Normal response will be Ã‚Â½
Explain that when they answered the question, they actually compared amount of pizza eaten to the amount of pizza available.
Ask them to compare in a similar way the number of girls in the classroom to the number of boys. (Example: 8/10). At this point, it is better to revisit fractions and refresh their memory about reducing fractions. 8/10 reduces to 4/5.
Ask several more examples. Make sure students understand comparison can be written in the form of fractions. Now simply tell them that “ratio” is a term conveniently used for comparison of two numbers, or to tell how one number is related to another number.
Ratio is usually written as a quotient of two numbers. It can also be written in a different form as shown below:
Example: 2/3 is same as 2:3
This new form will be useful when teaching the next lesson on Proportions.
*Teachers* Important Non-Intuitive Observations
Order matters in writing ratios. Explain drinking one can of soda out of 5 available cans (1:5) is different from drinking 5 sodas out of 1 (5:1). 1:5 and 5:1 are not the same.