Mathematical Emphasis
In Prime Time students will explore important properties of whole numbers, especially those related to multiplication and division. The investigations in this unit will help students to:

• Understand relationships among factors, multiples, divisors, and products;
• Recognize and use properties of prime and composite numbers, even and odd numbers, and square numbers;
• Use rectangles to represent the factor pairs of numbers;
• Develop strategies for finding factors and multiples, least common multiples, and greatest common factors;
• Recognize and use the fact that every whole number can be written in exactly one way as a product of prime numbers;
• Develop a variety of strategies for solving problems: building models, making lists and tables, drawing diagrams, and solving simpler problems.

Tips For Helping At Home
Questions To Ask:

• What do you need to find out?
• What did you do in class to get started?
• Have you solved similar problems that would help?
• Can you make a drawing (model) to explain your thinking?
• What would happen if…?
• What do you need to do next?
• How do you know your answer is reasonable?
• Has the question been answered?
• Are there any questions you want to ask your teacher?

Helping At Home

• Math is everywhere, yet many children don’t see it. Look for ways to point out and reinforce math skills at home. Involve children in tasks that require estimating, building, problem solving, reasoning, and computing.
• Look for games and activities that reinforce math and thinking skills.
• Invite your children to explain what was learned in math class. Have them teach it to you—this provides an opportunity for children to clarify their thinking and practice new skills.

Vocabulary Terms

Common Factor

A factor that two or more numbers share

Common Multiple

A multiple that two or more numbers share

Composite

A whole number with factors other than itself and 1

Exponent

A small raised number that tells how many times a factor is used. For example, 5³ = 5 x 5 x 5

Factor

One of two or more numbers that are multiplied to get a product

Multiple

The product of a given whole number and another whole number

Prime Factorization

Longest factor string for a number, composed entirely of prime numbers

Prime Number

A number with only two factors (1 and itself)

Proper Factor

All the factors of a number except the number itself

Mathematics Strategy—Two Ways to Practice Multiplication

• Have children fill out all the multiplication facts they know on a 12 x 12 Multiplication Table. The remaining facts are math problems to learn. Work with children to figure out answers based on other math facts they know. Practice these strategies during the week then recheck with a blank multiplication table.
• Have children use multiplication flash cards. Children should say the problem as well as the answer when practicing. Place facts that are known into a “Known” pile. The rest of the facts are problems to learn. Work with children to figure out answers to several of these problems based on other math facts they know. Practice these strategies during the week then recheck using the same process.

Mathematics Game—The Factor Game

Materials

Playing the Game

1. Player A chooses a number on the game board and circles it.



2. Using a different color, Player B circles all the uncircled proper factors of Player A’s number. The proper factors are all the factors of that number except the number itself.



3. Player B chooses a new number, and Player A circles all the proper factors of that number that are not already circled.



4. The players take turns choosing numbers and circling factors.



5. If a player circles a number that has no factors left that have not been circled, that player loses a turn and does not get the points for the number circled.



6. The game ends when there are no numbers remaining with uncircled factors.



7. Each player adds the numbers that are circled with his or her color. The player with the greater total is the winner.

Get to The Factor Board Game (for printing)

On-line version of the Factor Game