Math Lesson Plan: Adding & Subtracting Decimals

Lesson Opening

1. Quickly review the skills we have worked on so far: converting fractions and pictures into decimals, writing decimals in word form and comparing, ordering decimals. Explain to the children that they need to know all three of these skills for the test on Friday.

1. Now we are going to learn one more skill and it is very easy: adding and subtracting decimals.

1. What is a decimal? A decimal is just a dot on a piece of paper. So many people get mixed up when they see a decimal and they start doing all sorts of crazy things. You will soon find that adding and subtracting decimals is not that much different than adding and subtracting whole numbers.

Guided Practice

1. Give the children a number of addition and subtraction problems to do. Have the children who are doing the best job working independently come up and do the problems on the board.

1. There should be two types of problems. The first type should be with just whole numbers. The second type should use the same digits, but should have decimals in certain places.

1. Explain that you have to follow the same rules of addition and subtraction, i.e. you have to borrow and carry. To deal with decimal, you just bring the decimal down, making sure to keep it in the same place.

Independent Practice

1. Have the children complete a quick worksheet where they have to know how to represent a fraction and a decimal pictorially. Tell them that to pay attention because soon they will have to compare three decimals or fractions.

1. Show the children what a difficult task adding and subtracting fractions can be if you don't line up the decimals.

Closing

1. Ask students to share their answers.