As you continue to practice, you will need to add or remove material so your speech will fit into the assigned number of minutes. Most students and even experienced public speakers find it helpful to have a sheet of paper with key words or phrases in front of them. It is best not to keep a script or even anything with complete sentences on this sheet, because you will be tempted to read from it. You know from experience that when someone reads your attention tends to leave that speaker, making for a boring presentation and one you will less likely learn from. Index cards, when repeatedly flipped, can be distracting to the audience, so one sheet of paper may work better.
Some speakers like to use large type for their notes so they are easier to see at a glance.
As you practice, imagine that you are explaining things to a friend of yours. A conversational tone, like you would use to speak to someone over dinner, makes your audience feel comfortable. Some students find it helpful to videotape or audiotape themselves or to look into a mirror while practicing, while others would feel more anxious to do these things. It is very important and helpful to practice in as close a situation as possible to the real thing. You will probably be giving your speech in your own classroom.