Lesson 1: Getting Ready to Multiply

Day 2

Activity 3: Arrays and Repeated Addition

Materials: egg carton, fine point dry-erase marker (kit), whiteboard (kit)
Show your child an egg carton that has space for 12 eggs. Open the carton, and say, "An egg carton is a good example of an array. An array shows a number of objects in a set arrangement of rows and columns. The rows go across, and the columns go down. How many rows and columns does this carton have?" (2 rows, 6 columns) Explain that we call this a 2 by 6 array and that it shows the number 12. As you point to the rows and columns, say, "This array shows that we can make 12 by adding 6 groups of 2. We can also make 12 by adding 2 groups of 6." (Turn the egg carton to show this array.) Give your child the whiteboard and a dry-erase marker, and ask him to write two addition sentences for the egg carton array. Ask, "How can you show addition using this array?" He should write 2+2+2+2+2+2=12 and 6+6=12.

Now, write 4+4+4 on the whiteboard, and ask your child to draw an array of dots to show it. He should draw either 3 rows of 4 dots or 4 rows of 3 dots. Ask, "What's the sum of 4+4+4?" (12) Explain to him that arrays help us model repeated addition and that he will be using them to model another operation in coming lessons.

If your child needs additional practice with arrays and matching addition sentences to them, give him time to play the game at the following web link.
Web Link
Your child will complete the "Arrays and Repeated Addition" sheet by first writing addition sentences for the given arrays and then creating arrays and addition sentences to show a sum of 24.

Answer Key:
  • Box 1: 5+5+5=15 and 3+3+3+3+3=15
  • Box 2: 4+4+4+4+4=20 and 5+5+5+5=20
"Arrays and Repeated Addition" Answer Key

Activity 4: Equal Groups

Materials: fine point dry-erase marker (kit), whiteboard (kit)
Say, "Imagine that I need to make gloves for 8 people, so I need to know how many hands 8 people have. How might I figure that out?" Give your child the whiteboard and a dry-erase marker, and let him try to determine the answer. He may draw a picture (for example, of hands) or a diagram (such as an array) or he may write numbers to come up with the sum (16). When he's finished, ask him to explain how he found it.

Now, give him the "Equal Groups" sheet, and tell him to list things that always come in groups of the given numbers. He should write his ideas in the spaces provided. To help him get started, pose the following types of questions and examples as needed:
  • What else, besides hands, come in groups of 2? (eyes, ears, socks, twins)
  • What comes in groups of 3? (sides of a triangle, wheels on a tricycle, triplets)
  • Can you think of something that comes in groups of 4? (legs on a horse, sides on a square, wheels on a car)
  • How might you use what you know about time and money to come up with some ideas? (for example, a nickel is 5 pennies)
  • What are some things that you know about different animals that will help you come up with ideas? (for example, an octopus has 8 arms)
If your child needs more support to come up with ideas for the given numbers, allow him to search online by entering "things that come in groups of ___" (insert one of the target numbers). When he's finished with this sheet, he can store it in his Interactive Notebook for use in Lesson 2.