To assess prior knowledge, gather students in a circle. Distribute a Numeral Card with a number between 1 and 18 on it, turned face down, and a resealable plastic bag containing a set of 1 to 18 cubes to each student.
Ask students to compare their numeral card with the cubes in their bag to determine if they match. If the students’ numeral cards do not match the cubes in their bag, have each student display his or her card (taking turns one-by-one) to the other students in the class and ask them to trade their bag for one with the number of cubes that does match the numeral card.
If time permits, you might wish to have students verify that the bag of cubes that is traded does match the numeral card of the student displaying the card.
To begin the lesson, show the numeral 18 and tell students to clap their hands 18 times, counting aloud as they do so. Call on students to name other actions to do 18 times and have the class do them and count each time.
Give each student connecting cubes and the Ten Frames activity sheet.
Have each student count out 18 connecting cubes and ask them to show 18 in the ten frame. Then ask how they would model 17 in the ten frames.
Ask students to divide 18 cubes into two groups in as many ways as they can. Ask them to record the ways. After they have had time to work, encourage them to share how they divided the cubes. Encourage them to make statements, such as "I made a set of 7 and a set of 11 from 18 cubes." Record each decomposition where all the students can see.
Next, open the National Library of Virtual Manipulatives Virtual Spinner. Demonstrate for students how to create and use the spinners.
You may use only one computer for the demonstration or have students work together on multiple computers. You may wish to explore the other tools on this site to determine how they might be useful to you in other lessons.
Create an 11-part spinner by entering the numbers 10 to 20 in the left column. As you enter each number, call on a volunteer to choose a color for that section of the spinner. Then activate the spinner. Ask students to say the resulting number aloud and make a tower with that many connecting cubes, using ten of one color and completing the model with another color. Call on a volunteer to tell how many of each color he or she used to make the tower.
In the example below, the student might say, "I used 10 blue and 8 red cubes to make my tower of 18."
It may reinforce learning to repeat this activity several times using different numbers and choosing a different child to activate the spinner each time. Ask students to model each number that is selected with bean sticks.
After they have created various numbers and modeled them using two different colored cubes, call on three volunteers to spin the spinner. After each spin, ask all students to model that number with connecting cubes of two different colors (one for tens and one for the ones) and then trace, color, and label the tower. You may wish to ask them to model the number with bean stick pictures. Encourage students to take these sheets home to share with their families.
Ask students to add models of 17 and 18 to their bean stick record sheet, previously started in this unit. Collect these sheets for use in the next lesson.
