perceptions shaped by their experiences. In my daughter’s case, experiences gathered at the hospital, grocery
store, and local mall had molded her
perception.
Our students’ perceptions, and
the experiences feeding them, are as
diverse as their backgrounds. The difficulty comes when students’ experiences have produced misconceptions
that conflict with concepts we’re trying
to teach. If we aren’t aware of these
misconceptions, we may set students
up to run into the proverbial closed
door.
The gateway to effectively
uncovering and changing students’
misconceptions is predictive questioning. This strategy, used in conjunction with strategic discourse, is a
powerful tool (Chin, 2007). Learning,
especially the type of inquiry-based
learning encouraged in science classrooms, is a socially mediated endeavor.
Inquiry loses its punch without strategic discourse, whether that discourse
is with the teacher or among students
(Abell & Lederman, 2010). To get a
sense of how using predictive questions to uncover misconceptions
works, let’s examine a lesson I recently
taught my 12th grade astronomy
students.
Busting Myths About Gravity
I hoped this lesson would lead students to an understanding of the
evidence for dark matter in space.
I wanted them to understand that the
amount of gravity in our galaxy isn’t
enough to account for the high orbital
velocities of the stars near the galaxy’s
edge. Even stranger, stars moving
at those high velocities should be
escaping the galaxy’s collective gravity
and flying off into space—yet they
stay in their orbits. This implies that
something besides the visible mass we
can detect in our galaxy is holding the
galaxy together.
Before students could understand
this “missing mass” dilemma, they had
to have a foundational understanding
of gravity. The lesson started with
helping them grasp the law of universal gravitation,
which tells us that the force of
gravity (F) is affected by two things:
mass (m) and proximity (r). The
force of gravity gets stronger if objects
have more mass and if objects are
closer together; the converse of each
statement is also true.
Students needed to understand that
gravity acts as a tether holding objects
together, that objects can overcome
their gravitational tether when they
achieve high enough velocities, and
that the gravitational effects we see
within galaxies can’t be accounted for
by looking solely at the mass from
luminous matter (matter that can
be detected on the electromagnetic
spectrum). I used carefully planned
questions to lead them toward these
understandings.
I began by asking each student to
predict the orbital velocities of something familiar to them—the planets in
our solar system (What happens to the
orbital velocity of the planets as they
get farther and farther from the sun?).
I also asked them to explain their reasoning, providing a graphical as well
as verbal explanation; they would later
observe data on these orbits and revise
their explanations as necessary.
These questions were folded into
a protocol that I call the predict–
explain–observe–revise cycle—modified
from White and Gunstone’s (1992)
predict–observe–explain strategy.
Students predict the outcome of a
potentially discrepant event; explain
their reasoning (including graphically
if they are looking at the relationship
between variables); observe the actual
phenomenon or data; and engage in
strategic discourse in small groups—
which leads them to revise their explanations based on the evidence.
As I expected, most students predicted that orbital velocities would
increase as planets got farther from
the sun, giving explanations similar
to that shown in Figure 1. In physics
class, they had learned about linear
velocity, which explains that when an
object spins around, the outside part
of that object spins faster than the
inner part. I suspected I would have
to reveal—and break down—students’
misconceptions so they would realize
that this principle doesn’t apply to the
individual orbits of planets and stars.
Next, students collected and
observed and graphed actual data on
the orbital velocity of our planets.
Finally, in small groups they evaluated
this data, talked together about what
might explain it, and revised their
explanations for the orbital velocities.
If teachers aren’t aware of students’
misconceptions, they may set students up
to run into the proverbial closed door.
F=G
m1m2
r2