Dennis Yuzenas, a history teacher in West Palm Beach, Florida, recommends John Green's series of "crash courses." The items are fun and condensed.
Suggestions from Dennis: (1) play them slowly, piece by piece. (2) stop and ask questions. Check for "What happened before this event? What will happen next?" (3) Be patient. Resist the temptation to play the entire sequence. Go through it piece by piece. You don't have to do every segment in one sitting.
A better way to ask the question? "What are some ways that we can use to remember when WW2 started?"
That wording suggests that there are many roads to the top of the mountain and many ways to find the answer.
For frenetic pacing, this series of videos is useful. However, instead of simply identifying each period, why not gradually introduce each frame? Look at a photo, look up a wikipedia article, and ask about the time period.
"Was this before or after the Romans?"
"Where did this take place?"
"Who was involved?"
"Why didn't this happen before? What was necessary for this to take place?"
"What had to happen first to make this possible?"
