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4A
The Universe #2
On the basis
of scientific evidence, the universe is estimated to be over ten
billion years old....
4A
The Universe #3
Increasingly
sophisticated technology is used to learn about the universe....
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Black Holes 
Purpose
To introduce black holes and demonstrate how
space telescopes can provide data to support current
hypotheses.
Context
In this activity, students will explore a Web
resource called No Escape: The Truth About Black Holes on the Amazing Space website. This is
a module that introduces students to the science of black holes. Students
examine the anatomy of a black hole using a diagram of an accretion disk,
the event horizon, and jets of hot gas. This module also includes
subsections about myths, the history related to the discovery of black
holes, an animated trip to the center of a black hole, a discussion of
different types of black holes, and an opportunity to see actual Hubble
images that support the hypothesis of black holes.
Planning Ahead
Materials:
You should read the Teacher
Page , paying particular attention to student misconceptions and
prerequisites.
You may also refer to Science
background to refresh your understanding of black holes. The Black
Holes teacher sheet contains a list of vocabulary words that students
will encounter in the module. You may wish to go over this list with the
class since the science of black holes uses terminology that is likely not
familiar to most students. However, do not expect students to master the
vocabulary before they work on the module. Merely point out the words to
them and explain to them that when they encounter these words in the
activity, they can click on them to view a definition.
Motivation
Ask students: “What is a black hole?” Encourage a
brief discussion in which students can freely propose ideas about their
conceptions of black holes. Use these ideas to construct a definition of a
black hole based on class consensus. Write it on the chalkboard for future
reference. Then refer students to the Black Holes
Exploration student E-Sheet, which will direct them to Astronomers
pinpoint black hole at center of Milky Way.
Remind students to click on the interactive demonstration found in the
middle of the page. Let students go over it several times. Then, based on
this brief demonstration, refer students to your class definition of a
black hole and allow students time to revise it. Ask, "Are there still
some things about a black hole that you don’t understand?" Make a list of
these things.
Development
This is a self-directed module that will be
completed by students on their own, using the Black Holes
Exploration student E-Sheet. Students can work on their own or with a
partner.
There is quite a bit of specialized vocabulary surrounding the science
of black holes. So that students can have a better understanding of these
terms when they encounter them, you may wish to review the vocabulary
found in the Black
Hole teacher sheet. One way to approach this is to provide students
with a list of the terms that they might encounter and explain to them
that these terms will be underlined in the module. They can click on them
to look at definitions as they explore the resource. If you think it will
be helpful to your students, you can ask them to jot down these
definitions as they go along. However, make sure to emphasize that the
point of the lesson is to understand what a black hole is and that simply
being able to define new vocabulary is not the same as understanding the
process of how black holes are formed. The student sheet will ask them to
explain in their own words some of the key concepts embodied in this
vocabulary.
After students have completed the module, conduct a
complete discussion of the ideas covered in the student sheet. Then, refer
back to the original class definition of a black hole and allow students
to refine it based on their deeper understanding. It is important that
students be able to discuss the reasons why they have refined their
understanding and not merely substitute one definition for
another.
Assessment
The following questions can be used to assess
student understanding about black holes:
- What does a black hole look like? (A black hole itself is invisible
because no light can escape from it.)
- Are there any pictures of a black hole? If not, why not? (There are
no "real" pictures of a black hole. This is because black holes
themselves do not emit or reflect any light [that's why they are called
black holes], and they are too small and too far away to be imaged.
There are images of binary star systems consisting of one normal star
and one black hole, and of the central regions of galaxies that are
believed to contain black holes. Students can look at some examples
of the latter, taken with the Hubble Space Telescope, but these
pictures don't actually show a black hole; you need to study the motion
of stars to infer that there must be a black hole. )
- Could a black hole suck up all the matter in the universe? Why? Why
not?(A black hole has a "horizon," which means a region from which you
can't escape. If you cross the horizon, you're doomed to eventually hit
the singularity. But as long as you stay outside of the horizon, you can
avoid getting sucked in. In fact, to someone well outside of the
horizon, the gravitational field surrounding a black hole is no
different from the field surrounding any other object of the same mass.
In other words, a one-solar-mass black hole is no better than any other
one-solar-mass object [such as, for example, the sun] at "sucking in"
distant objects. )
You can also use the activity “Beats Us, You
Explain” also found on the No Escape: The Truth About Black Holes module
as an assessment. In it, students are asked to explain the concept of a
black hole to a targeted audience in 200 words or fewer. Images are
provided for students to use as illustrations for their descriptions.
Student work should demonstrate an understanding that the formation of
black holes is part of the process of star formation and destruction and
that technology has enabled us to understand more about this process as
advanced telescopes help to provide evidence about the existence of black
holes.
Extensions
Black
Holes contains a discussion of some of the popular myths about black
holes that have been perpetuated by fictional depictions of black holes.
Black
Hole Detection is an activity from Adler Planetarium curriculum in
which students simulate the motion of stars and identification of black
holes as part of star systems. This activity was developed for
middle-school students so high-school teachers will need to adapt some of
the teaching strategies to fit the maturity level of their classrooms.
However, it provides a concrete model in which you can check for
understanding of black holes by giving students the opportunity to
demonstrate what they know in a different context.
Similarly, Spaghettification
Flip Book, from the Adler Planetarium, also provides a different
context in which students can reinforce and/or demonstrate their ideas
about black holes. Spaghettification is the stretching of objects that
fall into a black hole. In this activity, students make a
spaghettification flip book that will demonstrate how the strong
gravitational pull of a black hole would stretch any astronaut unlucky
enough to encounter one in space.
Created :
06/10/2002 |