REDWOOD CITY, Calif. — Dozens of middle school students will be tested for hepatitis and HIV after their substitute science teacher allowed them to share needle-like instruments to prick their fingers for blood. The teacher, whose name was not released, was giving a life-science lesson to five seventh-grade classes Thursday at John F. Kennedy Middle School when he asked for volunteers to have their blood drawn using lancets so they could look at it under microscopes. Lancets are similar to the tools that diabetics use to test their blood sugar.