Multiply by 5
Students will be able to multiply single digit numbers by five and check that their answer ends in a five or zero.
- Show your students the first row of the Mystery Number 5 chart, while covering the rest of the chart with a piece of paper.
- Tell students that you want them to give a thumbs up once they think they have figured out what the mystery number is.
- Display one equation at a time, and read it aloud to your students.
- Call on students to share their answer after most of them are showing a thumbs up or you have shown the whole list of equations.
- Tell students that the mystery number five is special because lots of things come in groups of five.
- Ask students to share things that come in fives. For example, there are five fingers on a hand, five oceans of the Earth, nickels are five cents, quintuplets are five people, a school week is five days, and clocks have minutes grouped in fives.
- Explain that today they are going to use the strategy of skip-counting by fives to find the answer to multiplication problems with the number five.
Explicit Instruction/Teacher modeling(15 minutes)
- Give each student a Hundreds Chart worksheet.
- Tell them they are going to find and circle numbers that are a multiple of five by counting repeatedly by five on a hundreds chart.
- Remind your students that multiplication is repeated addition and that multiples are a series of answers (products) using the same base number multiplied by different numbers.
- Count aloud together as you circle the first few numbers. Say, "One, two, three, four, five. Let's circle five. Six, seven, eight, nine, ten. Let's circle ten. Eleven, twelve, thirteen, fourteen, fifteen. Let's circle fifteen."
- Explain to students that the first number circled, five, represents how many times the number has been multiplied (5 x 1 = 5). The second number, 10, represents that five has been multiplied twice (5 x 2 =10). The third number, 15, represents that five has been multiplied three times (5 x 3 =15).
- Have students complete the Hundreds Chart worksheet on their own.
- Count together by fives up to 100 once students have finished the worksheet.
- Ask students to share any patterns they noticed. If students don’t offer that all the multiples of five end with a five or zero, point it out.
- Ask students to double check that this is true by looking at the Mystery Number 5 chart worksheet.
- Tell students that another way to find the answer to a multiplication problem with a five is to skip-count using your fingers.
- Show that if they wanted to multiply five times a number they could count by fives and put up one finger each time until they have that number of fingers up. Say, "For 5 x 7 = ? count five, 10, 15, 20, 25, 30, 35. I know 35 is the answer because I have seven fingers up and my answer, 35, ends with a five or zero."
- Practice this strategy as a class or in partners.
Guided Practice(5 minutes)
- Show students the problem: 5 x 6 = ?
- Tell them that two people solved this problem, but they got different answers. One got 30 and the other got 31.
- Ask them to describe two ways that they could check the answer. (Skip-count and check that the answer has a five or zero in the ones place.)
- Show students the problem: 9 x 5 = ?
- Tell them that two people solved this problem, but they got different answers. One got 54 and the other got 45.
- Ask them to tell a partner the answer and explain how they know.
- Show students the problem: ? x 5 = 35.
- Ask them to describe to a partner how they can solve this problem.
- Call on a few students to share how they solved this problem.
Independent working time(10 minutes)
- Have students complete the Multiply by 5 Practice worksheet.
- Encourage them to do this worksheet without the hundreds grid in front of them.
- Have students highlight the multiples of five on the hundreds chart instead of circling the numbers.
- Encourage these students to use the hundreds chart when completing the independent practice.
- Give students a verbal exit ticket where they have to figure out the missing factor instead of the product. For example, 5 x ? = 40.
- Have students write and solve two-digit numbers multiplied by five using the same strategies learned today.
- Collect independent work to serve as a check for students' understanding.
- As students leave your room or transition to another activity, give them a verbal exit ticket asking each student a different multiplication problem with the number five as a factor.
Review and closing(3 minutes)
- Sit or stand in a circle with your students.
- Count by fives up to 50 by passing a high-five to the student sitting to the left of you in the circle. That student should then say the next multiple as they high-five the next person. Once 50 is said have students start counting by fives again until the circle is complete.