Lesson:What Is a Leap Year?

Conversation

Answer the following questions. You might be asked to write them down or answer them out-loud.

1. Do you keep a calendar? How do you use it?
2. How important is using a calendar for you?
3. Do you know what a leap year is?
4. Do you know anybody who was born on February, 29th?
5. How would you celebrate your birthday if you had been born on February, 29th? How would you feel?
6. How many days does a leap year have?
7. How does the leap year affect people?
8. Are you interested in astronomy?
9. Why is there a leap year every 4 years?

Vocabulary

Look at the vocabulary below. Take time to explore the links for their definitions in English and their translations to Portuguese. When you are done, make a sentence with each word. Ask your teacher if you should write them down or say them out loud.

DT   leap year

DT   born

DT   previous

DT   trouble

DT   understand

DT   full

DT   spin

DT   orbit

DT   drift

DT   sink

DT   set

DT   cool

DT   figure out

DT   specifically

DT   notice

DT   century

DT   astronomer

DT   actually

DT   revise

DT   version

DT   rule

DT   sync

DT   rotation

Video

Watch the following video but DON'T read the transcript yet.

After watching the video do this listening exercise.

Reading practice

Read the following transcript then do the associated reading comprehension exercise.

Transcript:

You probably know that this year 2012 is a leap year. And that means that this year we get an extra day on February, 29th. So instead of having 365 days this year, there will be 366. Great! An extra day, who really cares? Well people born on February, 29th on some previous leap year, also known as leaplings, they care, because they finally get to celebrate their real birthday. But, for the rest of us it’s just a day like any other day. Whoopdy doo. So, why do we go to all the trouble to have a leap year? Well, I’ll explain, now we all understand that day. One full day is actually how long it takes for the Earth to spin around exactly once. And a year is how long it takes for the Earth to orbit the Sun exactly once. So while the Earth orbits around the Sun in a full year, it spins around three hundred and sixty five point two five times. In other words, one full year equals 365.25 days. This is called the astronomical year. But here is the problem, our calendar year is only 365 days and that’s because there’s really no way to have a .25 day. And so those extra .25 days they just keep accumulating and what they do is make it so that the stars slowly drift out of sync with our calendar. So this is where leap year comes in to save the day. Every year we set aside those .25 days until the fourth year when they equal one full day. And then on the fourth year we put that extra day on February 29th , then we call it leap day. Bamm, we’re back in sync. That’s why February, 29th exists. Cool! But the real interesting thing, is how we humans figured this all out. It really was the Egyptians, who first figured out leap year.
They noticed by watching the stars, specifically the Sirius star. That the astronomical year was actually 365.25 days and they noticed this by seeing the Sirius star slowly drifting out of sync. But the western world wasn’t so fast to figure this all out. It wasn’t until many centuries later when Julius Cesar with the help of an astronomer, discovered just like the Egyptians first did that a year is really 365.25 days and they created the Julian calendar with the leap year that we know and love to fix that problem. Well done Julius! Well, not so fast. You see, if you want to get really exact about it, the astronomical year is actually 365.2422 days which is 11min. 14 sec. shorter than the Julian calendar. And that means in a hundred and twenty eight years from now, if we use the Julian calendar, we’ll be off again by one full day. So today, we use a revised version of the Julian calendar.
It’s called the Gregorian calendar because pope Gregory initiated it. The Gregorian calendar is just like the Julian calendar, but it has got a few more rules, so while every fourth year is a leap year. Every year that’s divisible by 100 are now no longer leap years. That means that years 1700, 1800, 1900 those were not leap years even knowing they normally would be. And here is another rule, if the year is also divisible by 400, then it is still a leap year. Which means that the year 2000 that was a leap year. And without those complicated rules, our calendars can stay in sync with the star for millennia to come. But, one more thing. Did you know that the Earth’s rotation is slowing at a way of .005 seconds per year? And that means in about two billion years we’re gonna have to add one more leap year to keep us in sync. But don’t worry we’ve got plenty of time to revise the calendar and fix that.

Writing practice

Write a couple of paragraphs talking about how you use calendars and how you usually schedule things. Make sure to use words you learned from the text and try to make it as long as you can.

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