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"The origin of our time system of 24 hours in a day with each hour subdivided into 60 minutes and then 60 seconds is complex and interesting," says Dr Nick Lomb, consultant curator of astronomy, from the Sydney Observatory.

Our 24-hour day comes from the ancient Egyptians who divided day-time into 10 hours they measured with devices such as shadow clocks, and added a twilight hour at the beginning and another one at the end of the day-time, says Lomb.

"Night-time was divided in 12 hours, based on the observations of stars. The Egyptians had a system of 36 star groups called 'decans' — chosen so that on any night one decan rose 40 minutes after the previous one.

December 2003 answer: It appears that the Egyptians were responsible for the 24 hour day. The Eqyptians were fond of counting in base twelve (instead of base 10 which is commonly used today). This is thought to be because they counted finger joints instead of fingers. Each of your fingers has three joints, so if you count by pointing to finger joints with your thumb you can count to twelve on each hand. This might seem arbitrary, but is actually just a strange as counting in base ten simply because we have ten digits.

The Egyptians divided the clock into 12 hours of daytime and 12 hours of night-time (or alternatively 10 hours between sunrise and sunset, an hour for each twilight period and 12 hours of darkness). This is known because of various sundials from the period which have been found to be marked with hours. Interestingly this means that hours started out changing in length with the seasons (as the amount of daylight vs. darkness changes).

Egyptians (who used base 12) developed a sundial which looked like a T-shaped bar placed in the ground with would divide the time between sunrise and sunset into 12 parts. Because of the seasonal change in the length of time between sunrise and sunset, summer hours were longer than winter hours! Historians theorize that the importance of 12 is based on the number of finger joints on each hand (not counting the thumb) or the number of lunar cycles in a year. The division of the night into 12 parts was achieved by Egyptian astronomers who observed the appearance of 12 key stars in the night sky. Out of these divisions was born the concept of a 24-hour day. However, seasonal hour length was used for many centuries, and fixed hours became common only after the appearance of mechanical clocks in 14th century Europe!

in timekeeping

3,600 seconds, now defined in terms of radiation emitted from atoms of the element cesium under specified conditions. The hour was formerly defined as the 24th part of a mean solar day—i.e., of the average period of rotation of the Earth relative to the Sun. The hour of sidereal time, 1/24 of the Earth’s rotation period relative to the stars, was about 10 seconds shorter than the hour of mean solar time.

In even earlier systems of timekeeping, an hour was 1/12 of a period of daylight or darkness—hence, variable in length with seasonal changes in the length of day and night. The custom of dividing the cycle of day and night into 24 periods seems to have originated with the ancient Egyptians.

A day consists of two 12-hour periods, for a total of 24 hours. An hour consists of 60 minutes. A minute consists of 60 seconds. Seconds are subdivided on a decimal system into things like "hundredths of a second" or "millionths of a second."

hat's a pretty bizarre way to divide a day up. We divide it in half, then divide the halves by twelfths, then divide the twelfths into sixtieths, then divide by 60 again, and then convert to a decimal system for the smallest increments. It's no wonder children have trouble learning how to tell time.

How long is a day? It's the amount of time it takes for the Earth to rotate one time on its axis. But how long does it take the Earth to rotate? That is where things become completely arbitrary. The world has decided to standardize on the following increments:

it’s Daylight Saving Time! Daylight Saving Time (or “Summer Time,” as it’s known in many parts of the world) was created to make better use of the long sunlight hours of the summer. By “springing” clocks forward an hour in March, we move an hour of daylight from the morning to the evening. On the first Sunday in November, we “fall back” and rewind our clocks to return to Standard Time.

Although Jupiter’s orbit, and therefore its year, is so much longer than the Earth’s, its day is much shorter.  The Earth turns on its own axis, turning away from the Sun and so giving us day and night, once every 24 hours.  Jupiter spins round much faster, turning on its axis once every 9.84 hours!

We experience some deep, quiet sleep and some active sleep, which is when dreams happen. You might think sleepwalking would happen during active sleep, but a person isn't physically active during active sleep. Sleepwalking usually happens in the first few hours of sleep in the stage called slow-wave or deep sleep.

Sleepwalking may run in families and sometimes occurs when a person is sick, has a fever, is not getting enough sleep, or is stressed.

Hours after bedtime, do you find your little one wandering the hall looking dazed and confused? If you have a sleepwalking child, you're not alone. It can be unnerving to see, but sleepwalking is very common in kids and most sleepwalkers only do so occasionally and outgrow it by the teen years. Still, some simple steps can keep your young sleepwalker safe while traipsing about. Despite its name, sleepwalking (also called somnambulism) actually involves more than just walking. Sleepwalking behaviors can range from harmless (sitting up), to potentially dangerous (wandering outside), to just inappropriate (kids may even open a closet door and pee inside). No matter what kids do during sleepwalking episodes, though, it's unlikely that they'll remember ever having done it! As we sleep, our brains pass through five stages of sleep — stages 1, 2, 3, 4, and REM (rapid eye movement) sleep. Together, these stages make up a sleep cycle. One complete sleep cycle lasts about 90 to 100 minutes. So a person experiences about four or five sleep cycles during an average night's sleep. Sleepwalking most often occurs during the deeper sleep of stages 3 and 4. During these stages, it's more difficult to wake someone up, and when awakened, a person may feel groggy and disoriented for a few minutes. Kids tend to sleepwalk within an hour or two of falling asleep and may walk around for anywhere from a few seconds to 30 minutes.

Sleepwalking and sleep terrors often run in families. Some things that can cause this are: Lack of sleep. This is the most common trigger for sleep terrors and sleepwalking. Illness Noisy or new environment Stress Some medicines

Sleep terrors and sleepwalking are related disorders of sleep that usually go away by adolescence.

Nightmares tend to occur after several hours of sleep, screaming or moving about is very uncommon, the dream is

usually elaborate and intense, and the dreamer realizes soon after wakening that he or she has had a dream.

I looked through the NO side. While I was doing so, I saw many errors. Most of the NO side complain that they have sports to do first, did it not occur to you that studies come first? If you fail school, the coach will (most likely) not let you play in that tournament/ game/ meet. As for the grammar errors on the NO side, I believe that many could use some Language Arts homework.

Students should have homework because it prepares them for high school and college. If we don't prepare them in middle school and elementary school they will be more overloaded in high school and college because they didn't expect it. Long Live Homework! Plus, if we don't have homework, kids will go home and forget everything they learned.

1. It helps you learn it better.2. It helps you understand it better.3. It tests you if you were listening while the lesson is being taught.4. It gives you problems to solve to help you get better at it.5. Homework is a good way to involve a child's family in the learning

Recent surveys show that children spend an average of 49 minutes a day on these games. If a child’s video-game console is in the bedroom, play time increases dramatically, to nearly three hours.

Video games hold special attractions for children with ADHD.

When a child strikes out in a baseball game, he’s doing it in front of a crowd of peers. But when he makes a mistake while playing a video game, no one else has to know.