Math Mammoth on Facebook

Math Mammoth on Google+







Blog

Free proportion videos online (pre-algebra/grade 7)

Find here free online math videos on proportions-related topics: solving proportions, unit rate, proportional relationships, and scaling geometric figures. These videos are suitable for pre-algebra / grade 7, and are aligned to the Common Core standards concerning proportions in grade 7 math. The videos are recorded in high-density (HD) and are viewable both here as well as at my Youtube channel.


Math Mammoth Ratios, Proportions & Problem Solving math book cover
72 pages
(includes answers)

PDF download $4.00
Printed copy $11.80, b&w
Math Mammoth Ratios, Proportions & Problem Solving

Sample pages (PDF)
Contents and Introduction
Solving Problems Using Equivalent Ratios
Scaling Figures 2
Problem Solving with Diagrams, part 1
Ratio Problems & Bar Models 2

Buy at Kagi
(credit cards, Paypal, check, cash, PO,
wire transfer, money order; see Kagi shopper help)

Buy at Lulu
(credit cards, Paypal, PO)

small flag of SpainEste libro en español



Solving proportions

Proportion is defined as an equation of the type (ratio) = (ratio). I show three different ways of solving proportions:
1) table
2) thinking of equivalent fractions
3) cross-multiplying

Then I solve several word problems that involve proportions using these methods.




Unit rates and more about proportions

A unit rate is a rate where the second term in the rate is 1 of something, such as $5 per $1 or 65 miles : 1 hour. You can always solve the unit rate from a non-unit rate by dividing. For example, if you have the rate $46 per 6.5 hours, divide $46 by 6.5 to get the rate per 1 hour.

I solve word problems involving unit rates, and also show how unit rate relates to SLOPE in a linear equation. Basically, slope gives you the unit rate!




Proportional relationships / Direct variation

How can we determine if two variables are in a proportional relationship or not? If you write a table of the values of the two variables, when one variable increases by some certain amount, the other should also increase by some certain amount. Another way to know is if you graph the equation that involves the two variables. You should get a straight line through origin, and if that is the case, the slope gives you the unit rate. (Or, just look at the equation that relates the two variables: it should be of the form y = kx.)

I also show an example of a non-proportional relationship, which ends up being an inverse variation. Proportional relationships are also called direct variation.




Scaling figures and the scale ratio

When a figure is enlarged or shrank proportionally, or when two figures are similar, the scale ratio is the ratio of one side of the figure to the corresponding side in the other. When the scale ratio is given, we can solve an unknown side. Or, if a set of corresponding sides is given, we can write a proportion to solve for the unknown side.

This lesson is meant for prealgebra or grade 7 math.




The videos match the lessons in my book Math Mammoth Ratios, Proportions, and Problem Solving (Blue Series book), or the lessons in chapter 2 of Grade 6-A. In any of those books, you will get MANY more practice exercises, word problems, and puzzles than what are shown in the videos, and also some lessons that are not in covered in this set of videos.

Math Mammoth Ratios, Proportions & Problem Solving math book cover
72 pages
(includes answers)

PDF download $4.00
Printed copy $11.80, b&w
Math Mammoth Ratios, Proportions & Problem Solving

Sample pages (PDF)
Contents and Introduction
Solving Problems Using Equivalent Ratios
Scaling Figures 2
Problem Solving with Diagrams, part 1
Ratio Problems & Bar Models 2

Buy at Kagi
(credit cards, Paypal, check, cash, PO,
wire transfer, money order; see Kagi shopper help)

Buy at Lulu
(credit cards, Paypal, PO)

small flag of SpainEste libro en español



By Maria Miller



Math Mammoth Tour


Confused about the different options? Take a 7-day virtual email tour around Math Mammoth! You'll receive:

An initial email to download your GIFT of over 350 free worksheets and sample pages from my books; 6 other emails on 6 subsequent days that describe the different series of Math Mammoth products, answering the most commonly asked questions, including "What is the difference between all these different-colored series?"

This way, you'll have time to digest the information over one week, plus an opportunity to ask me personally which book would be right for your child or students.

Note: You will FIRST get an email that asks you to confirm your email address. If you cannot find this confirmation email, please check your SPAM/JUNK folder.

"Mini" Math Teaching Course


This is a little "virtual" email course. You will receive:

An initial email to download your GIFT of over 350 free worksheets and sample pages from my books; 7 articles on important topics on mathematics education, including: multiplication tables, fractions, how to help a student who is behind, and the value of mistakes; 1 email about Math Mammoth books.

Note: You will FIRST get an email that asks you to confirm your email address. If you cannot find this confirmation email, please check your SPAM/JUNK folder.

Maria's Math News


This is my newsletter that comes out about once or twice a month. Peek at the previous volumes here.

You will receive:

An initial email to download a GIFT of over 350 free worksheets and sample pages from my books; Maria's Math News: my newsletter filled with math teaching resources, news, downloads, humor, and giveaways. The content is equally good for all of us who teach math.

© 2006-2014 MathMammoth.com