My 3rd period geometry class just finished participating in "Diving into Geometry" put on by CILC or the Center for Interactive Learning and Collaboration. It was fantastic. The three divers spoke to the students, got names, assigned jobs and interacted with them in such a way as they were so involved that the whole hour just went and none of the students were bored.
Since there were three divers, three students were assigned to do air checks every 5 mins. They taught the students various signs for communicating information when under water, talked about how to figure out distance using a fin kick. They covered area, volume, amount of water to fill a pool, the Pythagorean Theorem and a multitude of other topics. All my students were engaged, actively participating and at the end with five minutes left, they did not want to leave and even wanted to continue till lunch after the next period.
If your school can do video conferencing, the CILC has some fantastic programs whose cost is quite reasonable and the students find these programs really interesting and they love them.