This starter certainly lends itself to topics where specific events are important, but with a bit of imagination it can work in other areas too.
You are about to hold a press conference. As the pupils come in, give them their press passes, stating which media organisation they represent. Tell them to get their pencils ready as an important announcement is about to be made and their editors are expecting a full report from them.
Give the students a brief outline of the “event” – by no means the full story – and then ask if there are any questions. Initially they may be slow to get going, and you may need to drop a few “hooks” into the answers you give them.
This can be a surprisingly effective way to deliver a lot of content in a short space of time, and in a way which really engages the students.