Teach ratios using a ratio table by first teaching how to calculate missing values, and then use this new knowledge to teach how to compare ratios. To teach how to find missing values, address values that are present to find what is missing. To teach how to compare values, use this technique for both ratios, and then compare them to each other.
An example of finding missing values with a ratio table is if one column has number 2, a blank and 5, and the accompanying column has values 20, 40 and a blank. To find the missing values, use the first row ratio of 2 to 20, which simplifies to a ratio of 1 to 10. This allows the student to figure out the missing value in the first column as 4 and in the second column as 50.
Using this strategy, you can teach a student to compare ratios. For example, to figure out which swimmer is faster, each has values filled out for a umber of laps. The first did two laps in 10 minutes and four laps in 20 minutes, and the second did three laps in six minutes and six laps in 12 minutes. Simplifying values shows the first swimmer takes five minutes to complete a lap and the second swimmer takes two minutes, so the second swimmer is faster.