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Discovering that the Sun is a star and radiates light and the light reflects from other objects |
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OBJECTIVES:
VOCABULARY:
MATERIALS:
ELECTRONIC MATERIALS:
·
First 3 slides of Searching the Universe (old) slideshow
BACKGROUND:
A star is a ball of burning gases, mostly hydrogen and
helium. A star shines or glows because its gravity causes its gases to
fuse together. This process releases energy, hence the "shine". Our Sun is
only a medium-sized star. There are stars that are bigger, smaller,
hotter, and cooler. However, the Earth is very small compared to the Sun.
More than a million Earths could fit into the Sun. All life on Earth
depends on the Sun for light and heat.
Until the seventeenth century, most scientists thought that the Earth was
the center of the Universe, mainly because it appears that way to casual
observation. It is quite obvious that the Sun and Moon travel across the
sky from east to west. Ancient people often thought that the Sun and Moon
were gods with chariots such as Apollo and Athena, and gave them
personalities.
Part of this confusion was because while all sky objects appear bright,
some stars and galaxies (collections of stars) radiate light, while
the others only reflect light. This is sometimes difficult for
children to understand as well. When they look up at the night sky, they
see the brightly shining moon. How can it be that it does not produce its
own light, but yet it shines?
The stars make their own light. The Moon, planets, asteroids, natural
satellites, and comets shine by light reflected from the Sun. The Moon has
no light of its own, so it appears to have phases, cycling from new Moon
to full Moon and back every 29½ days. The phases happen because of the
angle at which the Sun's rays strike the Moon relative to the Earth, but
the exact mechanism will be explained in the later grades.
PROCEDURE: Goal: In this lab activity, students will learn that bodies in space can be classified in two ways: (1) those bodies that produce light (stars) and (2) those bodies that do not (planets, comets, meteorites, and most everything else in space).
1.
Review prior lessons.
Have the students tell you what reflection and refraction mean.
If they have forgotten, ask them what happens to the light when it
reflects? (it bounces back),
what happens to the light when it refracts (it bends).
2.
You
have time, so you can spend a couple minutes asking them if they remember
what they did in the last classes.
What happened with the light etc.
Children of this age like to tell you and once one starts
remembering there is usually a cascade;
BE SURE THEY HAVE TO RAISE THEIR HANDS TO TALK!
Steps 1 and 2 may take about 5 minutes.
3.
Then
tell them today we are going to talk about where light comes from in
space. Tell them if something
produces its own light it “radiates” light.
4.
Play
just the first three slides of
slideshow “searching the
universe”.
5.
Stop
on slide three and ask them what in space produces light (stars) and what
doesn’t produce light (they should say planets, moon, they may say
asteroids). Then tell them we
are now going to test the difference between things that produce light and
things that reflect light.
(about 5 minutes) 6. Turn off the lights and close curtains if possible (make the room as dark as you can).A flashlight or an energy ball can be an example of an object that produces its own light. Show students these items and ask them whether the light is produced inside it or not. A flashlight is like a star. If you put an object, like a basketball in a dark room, you will not see the basketball. However, if you shine the flashlight on the ball, you can see the basketball in the dark. The basketball is the Moon or Earth and the flashlight is the Sun. Demonstrate this in class. (about 5 minutes)
7. Turn
on the lights and talk about comets.
Ask them if they know what a comet is?
Comets also reflect light from the Sun. A comet is an object that
is made up of gases and "rocks" that orbits around the sun.
Comets do not pass Earth very often and ancient peoples were
frightened of them. 8. If you can make the room dark continue from # 9 - #13. If not have the ability to make a room dark, use boxes that you can shine line into and see if the students can figure out what is reflective and what is not. For example a white ball will reflect light but a dark ball would not.
Wrapping a ball in aluminum foil is good for making
an object that is very reflective.
Put a variety of reflective and non-reflective
items in the boxes. There
should be 1 to 2 boxes per lab table.
For this activity first have them try to identify items by looking
in the box without the flashlight.
Next have them try to identify items in the box with the
flashlight. Can they see more?
What items are easiest to see with the flashlight? You can add
things that glow by themselves like a glow stick and turn them on for the
second viewing of the box.
After they have had a
chance to look in the boxes with and without a flashlight
ask them some follow up questions along the lines of “what did you
see in the boxes without the flashlight?
Did anything in their produce its own light?
How do you know? What
could you see in the boxes with the flashlight?
What things produced light that made them visible?
Ask them where most of our light comes from during the day? (the
sun) what is it called when
something produces its own light (radiate)
What about at night?
(the moon and electric lights) Does
the moon produce its own light?
Where does the moon’s light come from?
It reflects light from the sun.
You can end here.
Go to #14 and play zoom
zoom song if you have time.
9.
This is a fun activity to have the students “live” reflection. Divide
students into teams of two.
Give each pair of students one "comet ball." (A ball with reflective
streamers.) Have them stand a few feet apart and gently toss the comet
ball back and forth. Make
sure they keep it under control.
This is done with the lights on and it should be easy.
10.
Then turn the lights off and ask students if they can see any comets when
they throw them to their partner. They should answer no (or at least not
as well). If it is really
dark there will be a lot of excitement.
11.
Next, let several teams be “stars”.
They will take turns.
The Stars get to hold flashlights and shine them on the comets. Have the
students throw the comets again. Ask them when can they see the comets.
They should realize that the comets are only visible when they come into
contact with the light. The comet is reflecting light, not producing
light. The students using the flashlights are representing stars.
12.
The students will each want to take a turn at being stars.
So let them throw the comets for about a minute while the stars
shine and then say STOP or FREEZE.
Switch and take flashlights from the stars and give them back the
comet balls and give the flashlights to new stars.
Do this for a couple of rounds—you may not have time for everyone
to be a star. (the whole ball
section should take about 20 minutes).
[Crowd control hints If they
are getting out of hand, Make EVERYONE
STOP and put the balls and
flashlights down and take their hands OFF completely then tell them they
need to control the comets or their team will lose their comet ball.
Then start again.
13.
After trading back and forth a
number of times collect all the balls and flashlights and do a review
(sitting on the carpet is good for this).
Ask them some follow up questions along the lines of “What did we
see that produced light when the lights were off?”
They should say the flashlight and the ufo balls (and anything else
that is glowing in the room.
Did the comets produce their own light?
How can they tell? Ask
them where most of our light comes from during the day? (the sun)
what is it called when something produces its own light (radiate)
What about at night?
(the moon and electric lights)
Does the moon produce its own light?
Where does the moon’s light come from?
It reflects light from the sun.
You can end here.
14.
ONLY
IF YOU HAVE EXTRA TIME.
If you find you have extra time you can play the Storybooks “zoom
zoom” (song). (it is about a
trip to the moon) First
graders love songs. They will
be very engaged. Ask them at
the end how they could see the earth when they were on the moon?
(Because it reflects the light from the sun!)
Tell them great job and you are done.
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