Ghost Particle, The
Students collect evidence to make inferences about an object hidden inside a
Students will be able to:
think critically and logically to raise questions.
identify questions that can be answered through investigation.
formulate and test hypotheses.
develop predictions and descriptions based on investigations.
- copy of the "Black Box Mystery" student handouts
- box with unknown object inside
1930, Wolfgang Pauli postulated the existence of a small elementary particle
with no charge and very little or no mass. He proposed this particle because
scientists were measuring less energy after a process known as beta decay than
before it occurred, conflicting with the law of conservation of energy. Pauli's
new theoretical particle balanced the energy equation. (The particle was later
named the neutrino in 1934 by Enrico Fermi.) Further studies showed that the
neutrino was also necessary to maintain the conservation laws of momentum and
spin. There are currently three known types, or "flavors," of neutrinos:
electron, muon, and tau neutrinos.
Billions of neutrinos pass through Earth each second, but since they are
particles with no electric charge and have very little mass, they only interact
weakly with other kinds of matter and are difficult to detect. Scientists study
neutrinos indirectly by looking at the results of their interactions with other
forms of matter such as heavy water or chlorine.
To help students understand the size of subatomic particles, you may want to
share the following chart with them and as a class develop a sample analogy
regarding atomic sizes. (For example, one sample analogy would be "If an atom
filled the distance from Boston to Cleveland, the nucleus would be about the
length of a football field; a proton would be about the height of a three-story
apartment building; and an electron and a subatomic particle called a quark
would be about a centimeter wide, or the width of a blueberry.")
in 1016 meters
100,000,000 cm or 1,000,000 m
(distance from Boston to Cleveland)
10,000 cm or 100 m
(football field length)
1,000 cm or 10 m
(height of 3-story apartment building)
about 1 cm such as a blueberry
Scientists have developed instruments to help them study subatomic particles,
such as particle colliders and detectors. In this activity, students will
experiment with what it is like to gain information about something they cannot
physically see. Students will generate and test questions to try to identify an
unseen object. Based on the evidence they gather, they will infer what is in
their mystery box.
of energy: States that the total amount of energy in a closed system
conservation of mass: States that the products of a chemical reaction
have the same total mass as that of the reactants.
lepton: A family of elementary matter (or antimatter) particles that
includes the electrically charged electron, muon, and tau and their antimatter
counterparts. The family also includes the electrically neutral
electron-neutrino, muon-neutrino, and tau-neutrino and their antimatter
neutrino: A lepton with very little mass and no electric charge.
particle: A subatomic object with a definite mass and charge. Currently
known elementary matter particles are grouped into categories of quarks and
leptons and their antimatter counterparts.
Discuss how scientists sometimes collect evidence to infer the presence of
objects they cannot see. Tell students that in this activity, they will collect
evidence to make inferences about an object hidden inside a sealed box.
Create each mystery box by placing a common classroom object (such as a roll
of tape, scissors, or a beaker) inside a box and sealing it with tape or a
Set up a table that displays 10 to 15 common classroom objects, some of
which are similar to or exactly the same as the objects in the mystery boxes.
Provide additional empty boxes as well.
Organize students into groups and distribute the "Black Box Mystery" student
handout to each student and a mystery box to each group. Explain that the
challenge is to design ways to gather information about a mystery object that
students can't see or test directly.
Point out that the mystery objects are similar to some of the objects on the
display table. Students can use information they know about these objects to
help them learn more about the unknown mystery objects.
After they have completed the activity, have students compare the process of
inferring the identity of a mystery object sealed in a box to inferring the
existence and number of neutrinos detected by their effect on another
substance. Then have groups consider how inference plays a role in their daily
lives. Explore group answers in a whole-class discussion.
As an extension, provide teams with a black box that has an object taped to
the bottom of the box. Provide teams with skewers, rulers, pencils, and grid
paper. Have teams measure their objects and draw them on grid paper. Ask
whether measuring made the object easier to identify. Discuss how specific
measurements sometimes help scientists better define things they cannot see.
Students will design a variety of tests to gather information about the mystery
object. For example, they might determine the weight of the object by comparing
the weight of the mystery box to the weight of an empty box. They might shake
the box and listen to the sound the object makes. Or they might try to
determine the object's shape by the way it strikes different points of the box
when shaken. They could then take a known object from the display table and put
it through similar tests. Students might also rule out objects that are
unlikely or impossible, such as objects that are too large to fit in the
If students arrive at immediate conclusions, direct them to return to the
evidence by asking questions like How do you know that? Remind students
to evaluate their inferences by comparing them to the evidence they've
collected. Inferences that don't include all of the evidence are not
necessarily wrong but may be less believable. Point out that there is a range
of plausible explanations, some being more likely than others.
Discuss with students whether the real identity of the mystery object should be
revealed. By not allowing students to see what the object is at the end, the
focus of the activity remains not on getting the right answer but on developing
plausible inferences, or conclusions, that are supported by evidence.
Student Handout Questions
What inferences can you make about the object? List them on a separate sheet
and include the evidence that supports them. Student answers will vary based
on the tests they conducted.
What situations in your daily life might call for inference? List the
situations and the evidence you use to support those situations. Student
answers will vary. One example of a daily life inference might involve
inferring whether someone is in the bathroom. Evidence such as a closed door,
the sound of running water, and a bathrobe missing from a sibling's bedroom
could be used to infer that someone is in the bathroom.
NOVA—The Ghost Particle
Read seven steps to making a good science film, learn of two scientists who
spent their careers searching for the solar neutrino, explore neutrino-hunting
projects worldwide, and view a time line detailing the pursuit of the elusive
How Do We Know
Protons, Electrons, and Quarks Really Exist?
Suggests ways of addressing the existence of invisible particles.
Solving the Mystery of Missing Neutrinos
Describes how scientists solved the solar neutrino mystery.
What's a Neutrino?
Provides a detailed look at the history of neutrinos, along with in-depth
reviews of the different experiments and devices used to detect neutrinos.
Tour of the Subatomic Zoo: A Guide to Particle Physics
by Cindy Schwarz and Sheldon Glashow. American Institute of Physics, 1996.
Introduces the ideas, terminology, and techniques of high-energy physics and
provides historical views of matter from the atom to the quark.
The World of Atoms and Quarks
by Albert Stwertka. Twenty-First Century Books, 1995.
Traces the history of atomic theory in physics and includes a guide to
The "Black Box Mystery" activity aligns with the following National
Science Education Standards (see books.nap.edu/html/nses).
Science Standard A
Science as Inquiry
Abilities necessary to do scientific inquiry
Science Standard A
Science as Inquiry
Abilities necessary to do scientific inquiry
Classroom Activity Author
Tanya Gregoire has taught at Brookline Public Schools in Massachusetts and is
coauthor of "Museum of Science Activities for Kids." This classroom activity
originally appeared in the companion Teacher's Guide for NOVA's "Hunt for Alien