abc  
 
Solutions and Samples
   
of student work
 
19.

a. The result is even.

 

b. The result is even.

  c. One number is even and one number is odd.
20. a.
  b.
21. No. Explanations may vary. Sample explanations:
  • because odd + odd = even
  • because every V-pattern is made up of an odd number of geese; so, if the number of geese in two V-patterns are added together, there will be an even number of geese, since
    odd + odd = even
 
Hints and Comments
 
   

Overview A further exploration of the sums of even and odd numbers is supported by using dot numbers and the concept of pairing. Students should now be ready to generalize about combining odd and even numbers.

About the Mathematics Problems 19-21 will help students generalize the following properties of numbers:

  • even + odd = odd,
  • odd + odd = even.

Planning After completing the problems on this page, many students may be ready to generalize about adding odd and even numbers. Decide whether you want to use problem 20 as a writing opportunity or as an assessment. Be sure to discuss students' answers to problem 21. Students may work in pairs or small groups on these problems.

Comments about the Problems

20. Informal Assessment This problem assesses students' ability to reason about patterns using pairing; symmetry; even, odd, and super-even numbers; symbols; and directions.
21. Students apply their understanding of the properties of odd and even numbers in a more complex situation. If students are having difficulty, remind them that a V-pattern always has an odd number of objects.

Extension Together with students, review all the rules for the sums of even and odd numbers. You may want to explain similar rules for multiplying odd and even numbers. The rules for multiplication are as follows:

  • even x even = even,
  • odd x even = even,
  • odd x odd = odd.

Writing Opportunity Problem 20 can be used as a journal writing assignment. Ask students to write their explanations about dot patterns in a way that would make sense to someone who has never heard of dot patterns.

  Mathematics in Context • Patterns and Symbols
Section C   Even and Super-Even 51

MATHEMATICS IN CONTEXT - Patterns and Symbols: V-Patterns- Sections A & C
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