Find out whether your students know how to work with fractions. Fractions provide the foundation for decimal calculations. More specifically, check whether the students can add, subtract, multiply and divide fractions. Also, students need to be able to simplify fractions; for example, 2/4 = 1/2. If you uncover any problems with fractions, thoroughly review fractions before starting to work on decimals.
Teach the students to convert fractions to decimals and vice versa. For example, 0.1 is 1/10, 0.01 is 1/100, 0.001 is 1/1,000 and so on. To ensure that the students understand the relationship between decimals and fractions, provide them with problems that require conversions. For example, let them solve the problem, 1.25 + 1/4. To arrive at the right answer (1.5 or 1 and 1/2), the students need to either convert 1.25 into a fraction (5/4) or write down 1/4 as a decimal (0.25).
Instruct the students to properly read decimals. For example, they should be able to say 12.47 as "twelve and forty-seven hundredths" or "twelve point four-seven." Knowing how to read decimals is essential for the students to be able to communicate about decimal numbers.
Visualize the decimals. You can use coins to help you. For example, $0.25 is a quarter of a dollar. It means that 4 * $0.25 = $1. One penny is 0.01 of a dollar, meaning that you need 100 pennies to equal one dollar. Give students examples of how decimals can help people count money. For example, if a cashier has only quarters and needs to give change of $2.25, he needs to give 2.25 / 0.25 = 9 quarters.
Cover the topic of how to perform addition and subtraction of decimal numbers. Essentially, tell children that these arithmetic operations are largely done as with other numbers. Do not be in a hurry and let the children take their time to understand the topic.
Teach students to round off decimals and why it is important. Rounding is important because it allows people to focus on the "big picture" and speeds up calculations. For example, if a child finds a T-shirt for $9.97, he should round up the price to $10.