Hockey pucks: They're small and heavy and — one Michigan college thinks — may be the perfect weapon against an active shooter on campus. Oakland University, a public school in Rochester Hills, near Detroit, is distributing thousands of 94-cent hockey pucks for just that reason. The distribution, which began earlier this month, stemmed from a March faculty active-shooter training session, which followed February's shooting at a Parkland, Fla., high school that left 17 dead. A participant at the training asked Oakland University Police Chief Mark Gordon what items people could use to defend themselves on the campus, which has a...