If you are giving a presentation in a class about history, you want to be as prepared as possible. In addition to planning what to say and memorizing dates and facts, you should also have some visual aids and other props that help you make your points. One to use, especially if you are covering a long period, is a timeline. While you can purchase printed timelines, they probably don't have the specific information you need. Make you own easily from poster board.
Put each piece of information on its own index card. For example; if you mention the Battle of Yorktown, have the date, place, combatants and the outcome. Don't be too detailed, since it has to fit on the timeline.
Use a marker to draw a line across the poster board. Write in the dates you cover at either end of the timeline.
Draw year, decade or century increment marks along the timeline. Which you use depends on the amount of time covered by the timeline.
Write in each piece of information from your index cards above the timeline, drawing a line from the information to date on the timeline when it occurred.
Add a descriptive title at the top of your poster board in large type. For example; if your presentation is on the Civil War, you might write "Major Events of the Civil War."
Be careful when creating time lines as an adult, these can cause a flash to the past for some which could result in the experiencing of a mid-life-crisis.
You may want to draw several drafts before deciding you have finished; the more you allow your brain time to stew on the subject, the more information you will come up with for your time line.