Yes, a great white shark did drag around a fishing boat in SF Bay this summer. But sightings are rare, except along the coast. If you want to introduce your grandkids to this voracious phenomenon head out to the Presidio this Saturday from 11-4. It’s the Sharktoberfest at the elaborately named Great Farallones National Marine Sanctuary Visitors Center. There will be lectures, a nautically themed costume parade and contest, live music, even a chance to build a model shark. Your progeny should go wild. Free.