Lesson 2

Counting by Fives

Est. Class Sessions: 2–3

Developing the Lesson

Part 1: Skip Counting by Fives

Count Hands and Fingers. Begin the lesson by reviewing skip counting by twos. Ask the class to find out how many hands are in the class. Skip count by twos to determine the total number of hands. Have students hold their hands in the air, then walk around touching each second hand as students skip count by 2.

Ask:

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  • How many hands do we have in our class? (Responses will vary.)
  • How did we count? (skip counted by two)
  • Is there another way we could count the hands?
  • How can we find out how many fingers we have in our class? (Possible responses: Count them one at a time; count them by five.)

Give each pair of students a sheet of 6-inch x 18-inch paper. See Materials Preparation. Have them orient the paper in the landscape position, so students can trace each other’s hands on the same sheet. See Figure 1. Remind students to spread their fingers out so that each finger is visible but not so far apart that both sets of hands will not fit. Ask them to outline their tracings with a marker or crayon so that each hand can easily be seen when displayed. Organize students into groups of 6 or 7 and ask them to post the drawings of their hands side-by-side. Focus students’ attention on one of the sets of hands displayed.

Ask:

X
  • How many hands are in this group? (Possible response: 12–14 hands)
  • How many fingers are on one hand? (5 fingers)
  • How many fingers are on four hands? (20 fingers)
  • How did you figure that out? (Possible responses: I skip counted by 5.There are 5 on the first hand, then 10, 15, and 20 fingers on all four hands. I counted each finger.)
  • How many fingers are in all the hands? (Possible response: 60–70 fingers)
  • How did you figure that out? (Possible responses: I skip counted by 5 to count all the fingers; I skip counted by 10 for each person or pair of hands.)

Start with one group of drawings and ask the students to count the fingers by ones as you or a student point to each finger. When the count reaches five, pause and write 5 under the first hand. When the count reaches 10, pause and write 10 under the second hand. Continue counting until all the fingers in that group of hands have been counted as shown in Figure 1. Have the students count the fingers by fives by reading the numbers written under each hand as you point to the numbers. Ask individual students to skip count aloud by fives.

Skip Counting by Five on the Number Line. Direct attention to the class number line with the multiples of five highlighted with self-adhesive notes. Tell students to slowly count by fives on the number line while a student is pointing to the hands from one group of six or seven students at the same time.

Ask:

X
  • How is our number line like the finger pictures? (Possible response: The number line is marked to help me skip count by five and our fingers are organized into groups of five to count by five. Both show that there are numbers between the fives.)
  • How is it different? (The number line shows all the numbers between the fives, and the finger pictures do not show the numbers between the fives.)
  • Which is quicker, counting each finger by ones or counting each hand by five?
  • Is there an even quicker way to count the fingers in a group? (Possible response: Skip count by 10 rather than by 5.)
  • Why is counting by tens quicker? (I do not have to say all those numbers.)
  • How is skip counting by fives like skip counting by twos? (I skip numbers to count when counting by fives or by twos.)
  • How is it different? (I skip more than one number when skip counting by five.)
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The number line with multiples of five and ten highlighted helps students visually represent the relationships among numbers and identify five and ten as benchmarks. These benchmarks will be used to estimate and perform operations.

Count by Five on the 100 Chart. Direct students’ attention to the display of the 100 Chart Master. Ask students to count, coloring each multiple of five red. Continue counting until reaching 100 with all multiples of five colored in. Have the students count by fives: 5, 10, 15 … 100.

Ask:

X
  • Which numbers did I color red? (the fives)
  • Which number did we count first? (five)
  • What do you notice about the red numbers? What pattern do you see? (Possible response: The numbers line up in two columns.)
  • What do you notice in the first column of red numbers? (All the numbers end in 5.)
  • What do you notice in the second row of red counters going down? (All the numbers end in 0.)
  • When we count by fives, what pattern do you see in the numbers in red? (All the numbers end in 5, 0, 5, 0.)
  • Do you think this pattern continues to larger numbers?
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Challenge students to count all the fingers in the class or the fingers for a part of the class (e.g., all the girls or all the boys). Give student pairs a few minutes to develop and discuss a strategy. After a brief discussion of each of these strategies, ask students to count the fingers in the classroom using one of the strategies discussed. Students can then compare strategies and counts.

Skip Count by Five on the Calculator. Distribute calculators to every student. Students are going to skip count by fives on the calculator and compare those counts to the counts on the 100 Chart just like they checked the counting by twos in Lesson 1. Have students start with zero on the calculator and
press  +  5  =. The window should show 10. To continue skip counting by 5, press  =. Each time the “hot” equal key is pressed, 5 is added. Compare the calculator numbers to the numbers colored red on the chart.

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Calculator Counting. Having them skip count by five on their calculator helps students connect skip counting to repeated addition.

Assign the Counting by 2s and 5s Homework Master.

ADVENTURE BOOK:
Student Activity Book:
Master: 100 C2&5
Answers
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SG_Mini
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SG_Mini
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Tracing hands for skip counting by fives
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