To fully comprehend decimals, students must understand place value, specifically the placements to the right of the decimal. When teaching these terms, enunciate the “th” sound clearly to avoid confusion between “hundreds” place and “hundredths” place. Help students recognize the relationship between fractions and decimals, and have them practice converting decimals to fractions as this will aid them when it comes time to convert decimals to percentages.
Percentages are based on the number 100. In other words, when percentages are written as fractions, the denominator will always be 100. If a shirt is on sale for 25% off the regular price, you are saving 25 cents off every dollar or 1/4 of the regular price. Percentages are used frequently in taxes, statistics and store sales.
Since teachers often educate the students in converting decimals to fractions before introducing percentages, students may find the following process easier at the start. Begin by converting the decimal to a fraction (.33 = 33/100), and from there, understanding that percentages are based on the denominator of 100, students can establish that 33/100 is the same as 33%. This process assists the student in understanding the concepts of decimals, fractions and percentages.
Once students understand the concept, there is nothing wrong with teaching them a shortcut to arrive at the solution. Decimals can be converted to percentages by multiplying the decimal by 100 or simply moving the decimal point two spaces to the right. Drop the decimal point, add the percentage sign, and the task is complete. For example, .93 = 93%.
Give each student a paper grid that contains 100 squares (10 rows down, 10 rows across). Instruct the students to create their own unique pattern by coloring in the squares of the grid using from four to 10 different colors. When the students have completed the task, have them list the colors they used and then determine what portion of the grid they colored each shade. They should list the portions in fractions, decimals and percentages. For example, if a student colored 17 of the blocks red, his listing would look like this: "red – 17/100, .17, 17%."