# 4 th Grade Division Lesson 11: Prime and Composite Numbers.

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4 th Grade Division Lesson 11: Prime and Composite Numbers

RULES OF DIVISIBILITY ARE BASED ON NUMBER PATTERNS. Today we want to test the math rule: What does divisibility mean? Think of things that come in groups. For example, 3 packages of pencils of 12 pencils each makes for a certain number of pencils. Is there a pattern you used to think about the total number of pencils?

Daisy Lily Many, many petals Each daisy petal has its own sepal Daisy has many anthers Each petal is its own flower A daisy is many flowers growing tightly together. Less petals Few sepals All its parts make one flower

The daisy is a composite flower since it is composed of many flowers. Some numbers are composite numbers because have more than two ways to be represented by multiplication. The lily is as a prime flower since all its parts make one flower. Some numbers are prime numbers because there is only two ways to represent them in multiplication.

Use arrays to find out if a number is prime or composite. Using your counters, take 6 counters and arrange them in two arrays.

Using your counters, take 5 counters and try to arrange them in arrays. Use arrays to find out if a number is prime or composite.

Using your counters, take 9 counters and try to arrange them in arrays. Use arrays to find out if a number is prime or composite.

Number Drawing of counters arranged in rows What are its factors? Prime Number Composite Number 5   1, 5 6  1, 2, 3, 6 7   1, 7, 8  1, 2, 4, 8

How are prime and composite numbers related to the daisy? What other conjectures can you make about the statement “Rules of divisibility are related to prime and composite numbers”? Journal Reflection: