Download Day 11: Investigating Patterns in Factors Grade 7

Day 11: Investigating Patterns in Factors
Grade 7
Description
factors for a range of numbers.
• Analyse the information and complete questions based on the information.
• Identify
Materials
• BLM 11.1, 11.2
• graph paper
• calculators
Assessment
Opportunities
Whole Class Æ Teacher Directed
Students connect their prior knowledge of factor, prime and multiple by doing
the following mental math problems. As students work through the
identification of the factors, they share strategies for determining factors (even
numbers divisible by 2, rules for divisibility by 9, etc.). Identify with them
organization strategies to ensure that no factors are omitted.
• A number is perfect if all its factors, other than the number itself, add up to
the number.
Students prove that 28 is a perfect number. Students determine the only onedigit perfect number. (6)
• A number is abundant if the sum of all its factors, other than the number
itself, is greater than the number. A number is deficient if the sum of all its
factors, other than the number itself, is less than the number.
Are 12 and 5 abundant or deficient numbers?
Pose the question: Are there patterns found in the factors of the numbers from
1-50?
Model the investigation by determining the factors of the first 6 numbers and
placing them on an overhead grid (BLM 11.1).
Factors of the Number
Minds On ...
A number is
divisible by 9 if the
sum of its digits is
divisible by 9.
Factors of 28 are
1, 2, 4, 7, 14, and
28.
28 = 1+2+4+7+14
Thus, 28 is a
perfect number.
Factors of 12 are
1, 2, 3, 4, 6, 12.
1+2+3+4+6>
12, thus 12 is an
abundant number.
Numbers that have
2 as a factor are
called “even”
numbers or
multiples of 2.
6
5
4
3
2
1
Number
Action!
Consolidate
Debrief
Skill Drill
Small Groups Æ Activity
Curriculum Expectations/Observation/Mental Note: Gather assessment
information about individual student’s number sense by observing while they
complete the investigation.
In groups of three or four, students continue the investigation for the numbers
7-50 breaking the task into smaller parts. Allow them to use calculators. They
record the results on graph paper for all numbers 1 through 50, so that patterns
are visible. Once they complete their grid, the groups answer the questions on
BLM 11.2, noting patterns that occur.
Whole Class Æ Clarification/Wrap-Up
Students share their solutions to the Factor Questions (BLM 11.2) with the
class.
To facilitate class discussion, use a completed overhead grid that illustrates the
solution.
Some students
may use
calculators
extensively, while
others will use
their knowledge of
number facts and
patterns to
complete the factor
grid.
Home Activity or Further Classroom Consolidation
For the numbers from 1 to 20, determine which numbers are abundant, perfect,
and deficient.
TIPS: Section 3 – Grade 7
© Queen’s Printer for Ontario, 2003
Page 49
11.1: Let’s Investigate
Name:
Date:
Are patterns created by the factors of the numbers from 1-50?
Above each number along the horizontal axis, place a dot opposite each of its factors.
Example: The factors of 6 are 1, 2, 3, and 6.
Complete the factor grid for numbers 1-7.
TIPS: Section 3 – Grade 7
© Queen’s Printer for Ontario, 2003
Page 50
11.2: Factor Questions
Name:
Date:
1. What observations and patterns do you notice on the factor grid (worksheet 11.1)?
2. List the numbers for which 5 is a factor.
How would you describe these numbers?
3. In two different ways, describe the numbers that have 2 as a factor.
4. Identify the numbers that have only two factors.
What is the name given to these numbers?
5. a) From the factor grid, list:
- numbers that have both 3 and 6 as factors.
- numbers that have both 3 and 9 as factors.
b) Compare the two lists. What patterns do you notice about multiples of 6 and multiples
of 9?
c) How might these patterns help a student who is trying to learn the multiplication facts
for 6 and 9?
6. On the factor grid, examine the column of factors for 12 and 18.
a) Where on the factor grid do you find the greatest common factor of 12 and 18?
b) Use the factor grid to determine the greatest common factor of 24 and 42.
7. Consider the number 120. How might you use the information in your factor grid to
determine all the factors of 120?
TIPS: Section 3 – Grade 7
© Queen’s Printer for Ontario, 2003
Page 51