Lesson: Adding Decimals

State Standard:

5.NSO-E.23

Standard Name:

Adding Decimals

Objective:

SWBAT find the sum and difference of decimals

Essential Question:

Why is place value of a digit important?

Word Wall Words:

sum

Do Now:

32.955 + 9.86
Line it up in different ways and have students try to figure out which way is correct

Opening:

Today, we are going to talk about the numbers you multiply together to get a product.

Direct Instruction:

When we are adding and subtracting numbers with decimals, we must line up our decimal points. Fill in zeros where numbers extend. Teach students to “Keep it Organized”

Guided Practice:

There is more than one way to do this. Show traditional algorithm and partial sums algorithm. Ask students if they do it a different way.

Independent Practice:

For these problems, it’s okay for you to do it however you are comfortable but you must show your work so I can understand how you are reaching your answer.

Math Journal:

In what other situations can estimating help you?

Closing:

Why do mathematicians line up decimal points when finding the sum and difference of numbers?

Center Options:

Give students a menu. They must select items to eat and drink. They will first estimate the cost, then figure out the exact cost. Then they will figure out the change out of $75.00. Students will change papers and check each other’s work for accuracy.

Differentiation:

Low: have them select fewer items; work with a partner. Model how to draw lines between place values to organize problems- color code if helpful

High: select more items, make change from a larger amount