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WINTER 1999
This
issue of Puddler takes a closer look at the functions of sleep,
both for animals and humans. It also presents information and experiments
about the properties of water in its liquid and solid states.
Special Feature:
"Do
Not Disturb"
Summary: Like humans, animals
need regular periods of rest. For some animals, this rest may simply
be quiet time when the body is relaxed. Other animals truly fall asleep.
These "down times" allow animals to conserve energy and stay
healthy. Animals may differ greatly in terms of when they sleep (day
or night), where they sleep (in sheltered spaces, on the ground, hanging
from trees, and so on) and how long they sleep (from quick naps to months
of hibernation).
K-3
Activity
4-6
Activity
More About...:
"...The Secrets Of Sleep"
Summary: By studying humans and
animals, scientists have learned quite a bit about the way sleep works,
as well as its importance. For example, scientists know that without
sleep, people grow confused and can even imagine seeing things. Sleep
is a time when the body relaxes, and its major functions slow down.
During sleep, the brain is able to sort through all the information
it's received during the day and store important facts as memories.
Sleep is also a time for dreaming. Scientists aren't sure what the meaning
of dreams is; they do know that in addition to people, mammals, reptiles
and birds dream. They have studied brainwave activity and found similar
patterns during sleep that people show when they switch back and forth
between deep sleep and dream states.
K-3
Activity
4-6
Activity
Young Naturalist
"Cool Facts
On Winter Water"
Summary: The properties of water in its solid state have important
effects on the land and living things in winter. For example, when water
freezes, it creates beautiful snow crystals. Water also is less dense
as a solid than as a liquid, because its molecules expand when it freezes.
This is important for wildlife. If ice sank through water, ponds and
streams would fill up with ice and kill life within them. Expanding
water also helps contribute to weathering. Water trapped inside rocks
expands as it turns to ice, and the pressure can be enough to make the
rocks crack.
K-3
Activity
4-6
Activity