Fractions, Decimals, and Percents

My sixth grade enrichment math class just finished a unit on fractions, decimals, and percents. These are probably the most practical lessons these children will learn throughout their years in school. As adults, most of us use these concepts on a daily basis. Our money system uses decimals. This is a revelation to some of my students.

When I present the fraction 1/2, almost everyone understands that the decimal equivalent is 0.5. When I present 1/4, the looks on their faces tend to change. My first question is, "What else do we call this fraction in English?" If I get no response, then I start talking about clock time. "What's another way to talk about 3:15?" Or I bring up money. "If one dollar is one whole, what is one fourth of a dollar?" By now someone has mentioned the keyword, a quarter.

This realization usually helps most older children who have some experience with money. One quarter is $0.25. Then I show them two quarters (2/4 = 1/2) is $0.50 which leads to 3/4 = $0.75. From there we go through all the tenths. 1/10 = $0.10, 2/10 = $0.20, etc. Every tenth represents a dime because a dime is one tenth of a dollar. This seems quite obvious to us as adults, but this sort of connection for many children is not necessarily apparent.

This can be taken through the twentieths (1/20 = $0.05) and the hundredths (1/100 = $0.01). The hundredths lead us to the presentation of fractions and decimals as percents. What does percent mean anyway? Per cent (pronounced as if one is speaking French because cent = 100) means per one hundred. How many cents are there in a dollar? Point out words that include cent: century, centennial, centenary, centipede, centimeter.

Let's go back to the halves. Most children understand that half of something is 0.5 or 50%. (Notice that 0.5 is the same as 0.50 not 0.05 which is another distinction that my students often miss.) See how the decimal point moves two places to the right to name the percent (which means that we are multiplying the decimal by 100).

The next step is tackling percent problems using direct translation. That will be the topic of another post.