M3.L22 Do Now Write a division expression for this area model and solve.
M3. L22 Objective: I can find factor pairs for numbers 1-100. I can determine if a number is prime or composite. Standard: 4.OA.4 Find all factor pairs for a whole number less than 100. Determine whether a given whole number in the range 1-100 is prime or composite.
Problem 1: Identify the factors and product represented in an array. Look at the below array model. What is the product, what are the factors?
Problem 1: Identify the factors and product represented in an array. Look at the below array models. What is the product for both models? Write the multiplication expression. Is there another way to represent the product? List the factors in order from least to greatest. How do we know when we’ve found all the factor pairs?
Problem 2: Identify the factors to determine prime and composite numbers. 2 x 8 = 16 What is the product? What are the factors? Think of all the ways to divide 16 equally (i.e. 2 groups of 8) Multiplication Sentences Factors (Least to Greatest) Prime or Composite? 16 2x8=16 The factors of 16 are:
Problem 2: Identify the factors to determine prime and composite numbers - Explanation
Problem 2B: Identify the factors to determine prime and composite numbers. 1 x 7 = 7 What is the product? What are the factors? Think of all the ways to divide 7 equally (i.e. 1 group of 7) How is the list of factors for 7 different than the list of factors for 16? Multiplication Sentences Factors (Least to Greatest) Prime or Composite? 7 1x7=7 The factors of 7 are:
Define “prime” and “composite” Composite: numbers with more than two factors. Prime: numbers with ONLY two factors (1 and the number itself) Multiplication Sentences Factors (Least to Greatest) Prime or Composite? 16 1x16=16 2x8=16 4x4=16 The factors of 16 are: 1, 2, 4, 8, 16 COMPOSITE 7 1x7=7 The factors of 7 are: 1, 7 PRIME
Problem 2C: Identify the factors to determine prime and composite numbers. Work with a partner (5 minutes) to discover 2 more prime numbers. Multiplication Sentences Factors (Least to Greatest) Prime or Composite?
Problem 3: Identify the factors of numbers and determine if those numbers are prime or composite numbers. Group 1 and 2 – 35 Group 3 and 4 – 23 Group 5 – 48 You can use a table to organize the factors if you’d like... When do you know you can stop searching for factors? When do the factors start repeating? Factor Pairs for 48 2 24
Lesson 22 Essential Questions Are all prime numbers odd? Are all even numbers composite? What numbers have an odd number of factors? Is the number 1 considered prime or composite?