Lesson Plan

Solve applied counting problems (committees, teams, selections, hands of cards) by deciding whether order matters and, for an unordered selection, counting with C(n,r)

Determine whether a problem requires permutations or combinations by asking "does order matter?"

Compute C(n,r) = n!/(r!(n-r)!) to count the ways to choose r items from n when order does not matter

Explain why C(n,r) = P(n,r)/r!: each selection of r items appears r! times among the permutations, so combinations count fewer arrangements than permutations for the same n and r

S 405. Exhibit knowledge of simple counting techniques S 603. Apply counting techniques