I did competitive speech and debate and business speaking events for going on seven years now, and have also been selected to speak at several public events so far. Speaking is wonderful once you get over stage fright, a really empowering feeling to know you have everyone's attention and have overcome the #1 fear in the world.
Four or five minutes seems like a lot, but in reality it isn't. The time will go by very fast.
If your teacher wants you to reinforce events, why not talk about other people in your class? Tease them, stir up inside jokes, go to each classmate one at a time and talk about your time with them.
You could also talk about something funny that happened while you were with your family or friends.
If you can, I would look up Oratory national speeches for National Forensics League (NFL) on youtube. I am not certain if there is any on there but the speeches from nationals the past couple years have been incredible and would really maybe un stick you to see someone else performing.