Lesson 1

Skip Counting

Estimated Class Sessions: 1

Developing the Lesson

Read and Discuss Two Ways to Count to Ten. Read Two Ways to Count to Ten by Ruby Dee as an introduction to skip counting. This book retells a Liberian folktale about jungle animals competing in a spear-flinging competition. To win, the contestant must fling a spear into the air and count to ten before it hits the ground. The winner used skip counting to count to ten before the spear hit the ground.

Questions to ask the students after reading the story:

X
  • Why was King Leopold holding the spear contest? (to determine a successor to his throne)
  • What is the challenge of the contest? (to count to ten before the spear hits the ground)
  • Who won the contest? (the antelope)
  • How did the antelope win the contest? (by counting to ten using skip counting)
  • Why did this strategy work? (It takes less time to count by twos to get to ten than it does if counting by ones.)
  • What are some different ways we can count to ten? (by ones, by 2s, and by 5s)
  • Can you skip count by 3s to get to ten? (No, if you skip count by 3, you will not land on 10.)

Simulate Leopold’s challenge by dropping a sheet of paper and asking students to count to ten before it touches the floor. Ask students to first count by ones and then by twos.

Practice Skip Counting by Twos. There are a number of ways to practice skip counting. Skip counting is a key arithmetic skill students must learn and master. It helps students understand the concept of place value and develop mental math skills to do addition. Students need a lot of practice aloud and with various representations to formalize this understanding.

To initiate skip counting as a class, ask eight students to come to the front of the room and stand with their arms in the air. As you point to each arm, ask students to count by ones. Then begin again. This time as the class counts, tell students to whisper the odd numbers and say the even numbers loudly as you point to every arm: one, TWO, three, FOUR, five, SIX, seven, EIGHT.

Repeat a few more times, each time with the whispers becoming softer and the loud numbers becoming louder. Eventually, students should say only the loud numbers aloud and say the whispered number in their heads. Reinforce this by clapping on the even (loud) numbers. Emphasize that students are counting the second arm in each pair and are skipping the first arm, thus the term “skip counting by twos.”

Ask:

X
  • What are some things that come in twos that we could skip count? (Possible responses: feet, eyes, ears, shoes, two wheels on bikes or scooters, mittens)

Repeat the count a third time, but this time point to and count every other arm (e.g., the second arm, the fourth arm, etc.). Practice skip-counting items in the room until students are comfortable with counting by twos.

Skip Count with Counters. Display an even number of connecting cubes. First have a student count them by ones. Then tell students you are going to count them by skip counting by twos. Have the class count with you as you separate out two at a time. Repeat with a different number of connecting cubes counting by ones and by twos. Emphasize that both methods of counting result in the same number.

Each time a set of cubes is counted, ask:

X
  • Count by ones. How many cubes are there?
  • Count by twos. How many cubes are there?
  • Did you count the same number of cubes each time? (Possible response: Yes, both ways end up with the same number.)
  • Which way of counting takes less time? (Skip counting is faster.)

Skip Count with the Even and Odd Chart. Refer students’ attention to the Even and Odd Chart from Unit 4 on display. See Figure 1.

Ask:

X
  • How can you use the Even and Odd Chart to skip count by two? (Possible responses: Just say the numbers in the even column (2, 4, 6, 8); whisper the odd column and say the even column; or say the odd column and whisper the numbers in the even column.)

Ask a student to demonstrate how to use the chart to skip count by two. Be sure to ask the student to start with the even column and count by two and start with the odd column and count by two.

Ask:

X
  • If you start on two and skip count by two, what numbers do you say loudest? (the even numbers)
  • If you start on two and skip count by 2, do you think you would say 26 loudly? (Yes, because it is an even number.)
  • If you start on one and skip count by two, what numbers do you say loudest? (the odd numbers)
  • If you start on one and skip count by two, name a number that you would say loudly. (Answers will vary. Possible responses: 11, 15, 33)

Skip Count with Number Lines. Ask students to focus on the class number line. Have students skip count by two as you point to the corresponding numbers on the number line. Gradually have students skip count to higher numbers using the number line for support. Use similar questions to discuss skip counting on the number line.

Ask:

X
  • If I start at zero and skip count by two, do I say the even or odd numbers? (even)
  • If I start at one and skip count by two, do I say the even or the odd numbers? (odd)
  • Why? (Possible response: Even and odd numbers take turns or alternate.)
  • Start at zero and skip count by two to 30. Would you land on 30? (yes)
  • Start at zero and skip count by two to 35. Would you land on 35? (no)
  • Are you counting with the even or odd numbers? (even numbers)
  • Is 30 even or odd? How do you know? (even; Possible responses: There aren’t any leftovers if I make pairs. If I skip count by two from zero, I land on that number.)
  • Is 35 even or odd? How do you know? (odd; Possible response: There is a leftover if I make pairs. If I skip count from zero by two, I do not land on 35.)

Continue with other examples, using the class number line and numbers up to 50.

Skip Count Using a 100 Chart. Display the My First 100 Chart Master. Ask students to count by ones from one to thirty. As they count, write each number on the chart. When you get to ten, ask students where they think you should write eleven. Moving down a row and going to the far left box should remind them of the numbers on the calendar and the way they read books.

After recording the numbers, ask students to count from one to thirty a second time. This time, point to the even numbers and ask students to skip count by twos. Color the even numbers red to emphasize the numbers they should say and which ones they should skip.

Ask:

X
  • Which numbers did I color red? (the even numbers)
  • Which number did we count first? (two)
  • What do you notice about the red numbers? (They are all in the same column.)
  • Name a number larger than 30 that would also be colored red if I continued skip counting by two. (Possible response: 50)

Skip Count with Calculators. Distribute calculators to every student. Explain that the calculator is a tool that can help them think about number patterns and can be used to check their calculations. Have students check the numbers colored red on the 100 Chart by having them start with 2 on the calculator and pressing + 2 =. The window should show 4. To continue skip counting by 2, press =. Each time the ”hot“ equal key is pressed, 2 is added.

Compare the calculator numbers to the numbers colored red on the chart.

X
  • What numbers show on your calculator? (The numbers that are colored red are the even numbers.)
  • When we say even numbers, what number do we start counting with? (2)
  • If you skip count by two from two, what numbers will you say, even or odd? (even)
  • If you skip count by two from two, what number is next? (four)
  • Compare that to the 100 Chart. Is [four] an even number?
  • I want you to skip count by two on the calculator but I want you to count the odd numbers. What do you have to do to the calculator to make that happen? (start at 1 rather than 0 or 2, and add 2)

Help students set up their calculator to add 2 starting at 1. Press: 1 + 2 = = =

Ask:

X
  • Look at the 100 Chart. What numbers show on the calculator? (The numbers that are not colored red or the odd numbers.)
  • How do you know that these numbers are odd? (Possible response: If I try to make pairs with the numbers, there are leftovers.)
X

Calculator Counting. If students do not have calculators with a “hot” equal key, they can skip count by twos on the calculator by pressing 2 + 2 = + 2 and so on.

Adventure Book:
Student Activity Book:
Master: 100C
X
SAB_Mini
+
Even and Odd Chart for adding models of even and odd numbers
X
+