Estimated division with numbers to 1,000 with a number greater than 10

General

The students learn to estimate quotients of numbers to 1,000 divided by a number greater than 10.

Standards

CCSS.Math.Content.4.NBT.B.6

Learning objective

Students will be able to estimate quotients with numbers to 1,000 divided by a number greater than 10.

Introduction

You play the division ball game. You throw a ball and name a division problem. The student that catches the ball gives the answer and then throws the ball back. You do this quickly.

Instruction

First you explain what the dividend, the divisor, and the approximately equals sign are. Then you tell the students that with estimated division, you always look for a number that is in the table of the divisor. Next you show how estimated division works step by step. Explain that you first look at the outcomes in the table. Look for which outcome is the closest to the divisor. For this you have to choose a number that is divisible by the divisor. You can also round the divisor to make a good estimated quotient. Unlike with estimated addition or subtraction, you can't round to any number. You need to choose a number that is divisible by the divisor. Show this step by step. You can also round to the nearest hundred. This is also possible, but you will be farther away from the exact answer. Discuss this with the students. Next the students practice estimated division on their own. After this, walk the students through the steps of solving a story problem with estimated division and have the students practice this on their own as well.

Check whether the students can estimate quotients by asking them the following question:
- How is estimated division different from estimated addition or subtraction?

Quiz

The students test their understanding of estimated division with numbers to 1,000 with a number greater than 10 through ten exercises. In some of these exercises the students must choose the correct estimated quotient, and for others they must estimate the answer to the problem. Some of the exercises are story problems.

Closing

You discuss once again with the students that it is useful to be able to estimate quotients, because then you quickly know approximately how much you can divide something by. Check if the students understand what estimated division is by discussing the following statements: is it useful or not useful in the different cases to estimate? You can easily estimate the quotient of the number of kilometers driven per person, but it is less useful to estimate the number of passengers on each airplane. Have the students determine what they find useful and less useful.

Teaching tips

When students have difficulty with estimated division with numbers to 1,000 with a number greater than 10, then you can first have them practice dividing hundreds or tens numbers.