Counting is not all it adds up to be — sometimes it involves multiplying. The lesson introduces permutations and combinations as ways of counting, depending upon whether order is important. Pupils learn about factorials and the formulas for permutations and combinations that use factorials. Pairs then work to fill in tables with examples and solutions to permutation and combination problems.

Concepts

permutations, combinations, factorials, fundamental counting principle

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Additional Tags

math

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Instructional Ideas

• Demonstrate permutations and combinations by selecting class members to stand in a line or gather in a group
• Have classmates determine the number of combinations for a combination lock and whether any two people at the school could possibly have the same one

Classroom Considerations

• Ensure the class understands factorials and simplifying expressions with factorials before moving on

Pros

• Contains instructor guidance on how to introduce the concepts
• Includes suggestions for differentiation of the instruction

Cons

• None

Common Core

HSS-CP.B.9 MP4 MP5 MP7