As I Tweeted earlier today, it’s a deflating feeling when you realize that you have to move your clocks forward this weekend. That’s especially true of you’re the parent of toddlers who have been on a sleep strike for a few weeks.

If you or your students are wondering why we (most of us in North America) have to change our clocks this weekend, here are few short explanations.

Even though it is not about daylight saving time, this TED-Ed lesson about the standardization of timezones is worth watching.