Three of the hardest concepts to grasp in mathematics for
students of any age are proportional thinking, ratio and rate. However, they
are quite simple once we know a little bit more about them.
Small explains proportional thinking or proportional reasoning as the way two amounts relate to each
other multiplicatively (pp. 312). That means, the relationship between two
amounts, when the value of one amount is always a constant multiple of the
corresponding value of the other. It is the main topic with the subgroups ratio and rate.
Ratio
describes the relationship between quantities of two values with the same unit.
This relationship indicates how many times the first number contains the second.
There are two different types of ratios:
a)
Part-to-Part ratios, which compare two parts of something
b)
Part-to-Whole ratios, which compare a part of something to its whole.
![]() |
Zapanta, D. (2015, September 22). Determining Ratios [Online Slide]. Retrieved from http://bit.ly/2yLXsOR |
Rate,
on the other hand, is a comparison of two values with different units. Check out Math
Gains for more information. One of the most useful abilities in life is being able to determine
unit rate. Small describes a unit rate as an equivalent rate where the second
term is 1 of that unit (pp. 320).
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Ms. Smith. Unit Rates R' Us [Online Slide].
Retrieved from
|
Now let's compare. Both ratio and rate are often expressed
as fractions, contain two terms, and can be used to create equivalencies, such
as equivalent ratios or equivalent rates.
And they both are both constantly used in everyday life. For
me, I use ratios when I am baking muffins. I need to know the ratio of eggs to
flour, so that when I make more or less than the recipe calls for, the muffins
still come out fluffy and delicious. Rates are great when determining how many
calories I am eating per serving of pizza, or my hourly wage, or determining my
running pace in meters per hour. I am also constantly finding myself comparing
products in the grocery store about the better; which item can I buy more of for
less cost.
Ratio of an igloo's
circumference to its diameter = Eskimo Pi
References:
Small, M. (2017). Making Math
Meaningful to Canadian Students K-8, (3rd ed.). Nelson Education.