4th Grade Decimals: Math Help and Problems

Teaching Decimals to 4th Graders

Background

Fractions

Coming into 4th grade, a child should understand that a fraction represents a part of a whole number (i.e., 9/10 is almost 1). Children at this level should also know that two equivalent fractions, such as 1/2 and 2/4, represent the same part of a whole number and have the same value. In addition, 4th graders should also know that whole numbers can be written as fractions (for example, 4/2 is the same as 2). Also, by the 4th grade a child should be able to:

1. Find or place basic fractions on a number line divided into equal parts between zero and one (i.e., 1/2 would be a point midway between 0 and 1 on the number line).
2. Understand the difference between fractions that have either the same denominator (1/3 and 2/3, for example) or the same numerator (2/4 and 2/5).

Place Values

Your child has been working with the concept of place values in whole numbers since kindergarten. By the time he reaches 4th grade, he should be fluent in naming and finding numbers in place values to the thousands, which includes ones, tens, hundreds and thousands. Children need a strong understanding of place value in order to be successful with decimals. If your child is struggling with place value, you may want to help him make a place value chart before he starts 4th grade.

New Topics

Place Values

After reviewing place values to the thousands, your child will learn that decimal place values are similar to whole number place values except that the names end in 'th' (e.g., tenths, hundredths and thousandths). The place values begin from the decimal point. Whole number place values go from right to left; decimal place values move from left to right. It can be helpful to make a visual chart for future reference in class and at home.

Fractions and Decimals

Introduce decimals as being another way to express a portion (or fraction) of a whole number. Demonstrate that fractions with denominators of ten or 100 can be easily turned into decimals and are read the same way. For example, 1/10 and 0.1 are both read as one tenth; 43/100 and 0.43 are both read as forty-three hundredths.

In 4th grade, your child will be adding fractions with denominators of ten and 100 (among others). When he has added two fractions with these denominators, he will likely be asked to also write the answer in decimal form.

In addition, your child will learn to compare decimals. She will be taught that in order to compare decimals, the decimals must be referring to the same whole. She will learn to record comparisons by using the symbols <, = and > (less than, equal to, and greater than).

Problems

In most cases, students don't learn to add and subtract decimals until 5th grade. As a result, decimal problems in 4th grade generally follow formats such as:

1. Write 7/10 as a decimal.

Answer: 0.7

2. Write 7/100 as a decimal.

Answer: 0.07

3. Add 7/10 and 7/100; write the answer first as a fraction and then as a decimal.

Answer: 7/10 + 7/100 = 70/100 + 7/100 = 77/100 or 0.77

4. Which is larger - 9/10 of a pizza or 0.09 of the pizza?

Answer: 9/10 > 0.09

5. Which would you rather have - 3/10 of a dollar, 30¢ or 0.3 of a dollar?

Answer: It doesn't make any difference because they are all the same.