March 28, 2011 2:32 pm Debating Teacher Tenure In California, teachers earn tenure after two years in the classroom. Supporters see tenure as a way to protect teachers from unfair firing. Critics say it’s an outdated measure keeping bad teachers in the classroom. US & World Videos 2:42 Forecast: Warm day, Saturday rain 3:05 Downtown First Thursdays offers new hope to struggling SF merchants 1:02 Crews knock down 2-alarm structure fire in SF's Nob Hill 1:11 24-hour online fundraiser underway for Peninsula nonprofits 1:43 Kari's forecast: Warm day, Saturday rain