Addition with decimal numbers up to the hundredths place

General

Students learn to add decimal numbers up to the hundredths place, they also learn to solve story problems involving decimal numbers.

Standards

CCSS.MATH.CONTENT.5.NBT.B.

Learning objective

Students will be able to add decimal numbers up to the hundredths place.

Introduction

Students practice placing the decimal numbers on the number line. They do so by drawing a line from the decimal number to where it belongs on the number line.

Instruction

Discuss the importance of adding decimal numbers. You can use decimal numbers to find weight and add money. Ask students if they know any other situations in which they can add decimal numbers. Use the example on the interactive whiteboard to discuss the steps of adding two decimal numbers with decimals in the tenths place. Tell students to start by adding the fist whole number and decimal number with the second whole number. Then add the second decimal number. Then show students a second example in which the whole numbers (or number before the decimal point) are added, and then the decimals (or numbers after the decimal point) are added, and that the two are then added together. Have students practice adding decimal numbers individually or in pairs, and tell them that they can select which method to use. Next show students how to add when you have two numbers after the decimal point (or hundredths). Show students that the steps are exactly the same as with tenths, namely add the first whole number with the decimal point to the second whole number. And then add the second decimal number. Alternatively you can show them to add both whole numbers and both decimal numbers, and then add the two together. Again, have students practice individually or in pairs, but this time adding hundredths. Next discuss story problems with the students. Teach students that there are steps in how to solve a story problem. Step one is to determine what kind of problem it is, the second step is to determine the numbers required for the problem. Third step is to say or write the problem, and finally the fourth step is to solve the problem. Walk through the first problem together as a class and then ask students to work in pairs to solve the next story problems. Remind them to use the four steps.

Check that students are able to add decimal numbers up to the hundredths place by asking the following questions:
- What are the steps to solving a story problem?
- What is one way to solve adding decimals?
- How would you add 4.13 + 0.55?

Quiz

Students are given a set of 10 questions in which they must add decimal numbers up to the hundredths place. The problems are abstract and story problems.

Closing

Remind students the importance of being able to add decimal numbers up to the hundredths place. Either individually or as a class, ask students to solve the given addition problems. Have students explain their strategy. To close the lesson, students must pick a character. They then leap with the character to an arrow on the number line. Then they leap again. They must add the total of their fist and second leaps. (Example: I select the frog. My first leap is to 0.41 and my second is to 33.21, I add them together for a total of 33.62)

Teaching tips

Students who have difficulty with this learning goal can be supported by making use of a number line. By representing the addition on the number line it can help make the decimal numbers more tangible.