Khan Academy
Introduction to Ratios
What a ratio is and how to write one to compare two quantities.
Watch on YouTubeUse ratios and rates to compare quantities, then use proportional reasoning to solve real-world problems.
Quick read-throughs in plain language — then hit the videos below.
A ratio compares two things. 2 cups flour to 3 cups sugar = 2:3 (or 2/3 or "2 to 3").
Order matters! Flour to sugar (2:3) is not the same as sugar to flour (3:2). Multiply both parts by the same number to get an equivalent ratio — like 4:6.
Try it
Write the ratio of 5 dogs to 8 cats.
By the end of this unit, you should be able to:
Each video covers one topic from this unit — read the short blurb below to find the right one.
What a ratio is and how to write one to compare two quantities.
Watch on YouTubeMore practice turning a rate into a unit rate.
Watch on YouTubeSpot when two quantities grow together at a steady rate.
Watch on YouTubeShrink fractions to simplest form — useful before comparing ratios.
Watch on YouTubeAdam's curated problem sets — preview here or open in Google Drive.
Hand-picked links from Khan Academy and trusted worksheet libraries.
A few quick questions to make sure the big ideas stuck. Retake as many times as you want.
Unit 2: Ratios & Proportional Relationships
A car drives 180 miles in 3 hours. What is the unit rate in miles per hour?