Does Light Bend?
During this investigation, you are going to explore how light
works. You will be exploring the testable question, “Does light
bend?” To do this, you will make some predictions, follow the
directions on the lab worksheet using a large straw and a light,
and record what you observe. Your conclusions will be based
on your observations, so try each test a couple of times and
look closely to see what the light is doing and how it looks to
you each time.
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
1 of 12
Does Light Bend?
Suggested Grade Span
3–5
Task
During this investigation, you are going to explore how light works. You will be exploring the
testable question, “Does light bend?” To do this, you will make some predictions, follow the
directions on the lab worksheet using a large straw and a light, and record what you observe.
Your conclusions will be based on your observations, so try each test a couple of times and
look closely to see what the light is doing and how it looks to you each time.
Big Idea and Unifying Concept
Change and constancy
Physical Science Concepts
Properties of matter
Transfer and transformation of energy
Mathematics Concepts
Graphs, tables and representation
Measurement
Time Required for the Task
Approximately 45 minutes (including introducing and laying the ground rules).
Context
This is one of several science investigation stations that I set up in my classroom during a miniscience circus. The students were exposed to the scientific method earlier in the year and
continued to build upon their skills practice through independent work at these stations. The
students did not have any prior work with me on the topic of light for what they were asked to do
in this station. The focus was not so much on learning about the concept of light as on the
scientific skills of observing and drawing conclusions from data/observations. The students'
findings and observations gave me a starting point for more direct instruction on the topic of
light; therefore, this can be considered an inquiry assessment task to guide further planning for
instruction.
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
2 of 12
What the Task Accomplishes
This investigation task is a good introduction to applying some aspects of scientific method and
scientific inquiry. It allows the teacher to assess scientific literacy – the knowledge and skills
related to scientific exploration that students have already acquired. The following aspects of
the scientific method included in this activity are: testing a hypothesis based on a prediction,
collecting and recording data, and analyzing data to draw conclusions. Some students might
also use their observations to challenge misconceptions and raise some new questions about
the nature of light. I stress the importance of making a prediction – not making a “correct”
prediction, which many students believe they are supposed to do. Predictions should be based
on prior knowledge and experiences, and that is something for the teacher to consider when
noting the predictions that students make and in guiding their progress.
How the Student Will Investigate
Students work alone at these stations. The materials are left on a tray, and students use a
direct light source from a GrowLab (a system of shelves and lights for growing plants) stationed
in the classroom. The students read and interpret the drawings on the lab sheet that gives the
directions. Then, they take some time to think about what they will be doing and what they
might see. They record their predictions, testing first the bent straw and then the straight straw.
(I encourage them to do both tests several times.) Finally, they draw some conclusions from
their observations. (Many of my students needed to be reminded to complete their conclusions
before leaving the stations.)
Interdisciplinary Links and Extensions
Science
I would not end the inquiry here; many more tests can be conducted to determine whether the
light is being reflected or absorbed by different materials. Discussions about colors of winter
and summer clothing, building materials, room-darkening shades (transparent – translucent –
opaque), aluminum foil, etc., would make more connections for students, since light and heat
energy are often associated with each other and behave similarly.
This activity can also lead into many other studies (some in later grades) that involve concepts
about the nature of light, such as: light traveling from the sun, moon, and stars can be seen
from earth only when earth is turned toward the heavenly object or when light is reflected from
it; the magnitude of light coming from stars is related to their size and distance from the earth;
because light travels at a known speed, we can make predictions about distance (in light years)
of stars and planets from us; light is a form of energy, and energy can be transformed into other
forms; light energy is absorbed by some objects and emitted by others; light is made up of
many colors of light, even though it looks white; differences in wavelengths are perceived as
different colors; and an object can be seen when light waves reflected or emitted by that object
enter the eye. Prisms, mirrors and various light sources can provide opportunities for more light
investigations.
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
3 of 12
Social Studies
Light, and the way it travels, has been widely used in communications, from flashing lights for
Morse Code, to lighthouses, to signal lights at airports, to fiber optics, for example. Students
could research the history of inventions such as the light bulb, noting the many (about 2000)
materials that were tested to find a filament that would work (the scientific method in action). A
unit of study on inventions that use light in some way might also expand understandings of light
– from cameras to lasers. A study of types of homes in very sunny locations can also reveal
aspects of the nature of light.
Mathematics
Students could try different light sources or different light wattages, measuring the distance
across a room that the light travels. (A larger, easily darkened room is best for this type of
activity.) Findings could be used to create a graph or chart.
Teaching Tips and Guiding Questions
Make sure that the straws you use are large enough and can easily bend. Since they can be
reused, it is worth investing in some good ones. I found that the cafeteria straws had too small
an opening for my students to see the light. This caused more confusion than it was worth.
Some guiding questions could include:
• What is your prediction? What question are you trying to answer?
• What differences did you see between the bent and straight straw?
• What did you observe? Can you make the light reflect in many different directions? Why do
you think this happens?
• How far did the light reflect? Why do you think this happens?
• What are you conclusions? Can you support your conclusions (give examples) using your
data/observations?
• What do you think you have learned about light? What do you still wonder about?
Concepts to be Assessed
(Unifying concepts/big ideas and science concepts to be assessed using the Science
Exemplars Rubric under the criterion: Science Concepts and Related Content)
Physical Science – Properties of Matter: Students observe the physical properties of light:
light travels in a straight line until it hits an object; light can be reflected or absorbed.
Physical Science – Transfer and Transformation of Energy: Students explain that light is a
form of energy and can be reflected or absorbed by objects it strikes. By observing patterns of
how light behaves, students begin to understand the effects of changes, such as decreasing
and increasing intensity, attend to the change and begin to describe it (change and constancy).
Mathematics: Students make precise measurements and use graphs, tables and
representations appropriately.
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
4 of 12
Skills to be Developed
(Science process skills to be assessed using the Science Exemplars Rubric under the criteria:
Scientific Procedures and Reasoning Strategies, and Scientific Communication Using Data)
Scientific Method: Observing, predicting/hypothesizing, collecting and recording data, drawing
conclusions, communicating findings, challenging misconceptions and raising new questions.
Other Science Standards and Concepts Addressed
Scientific Method: Students describe, predict, investigate and explain phenomena.
Scientific Theory: Students look for evidence that explains why things happen and modify
explanations when new observations are made.
Physical Science – Properties of Matter: Students observe and describe physical properties of
light.
Physical Science – Transfer and Transformation of Energy: Students observe that light is a
form of energy and can be reflected or absorbed by objects it strikes.
Suggested Materials
This inquiry task requires little advanced preparation and minimal materials to be carried out
successfully. Only a large straw (with a bending joint) and a light source are needed. A
flashlight with a strong battery or a small electric light with no more than a 60-watt bulb can also
be used. It also helps to be in a somewhat darkened space, so the light can be easily seen.
Refer to the Sample Worksheet on page 7.
Possible Solutions
Students should be able to determine that they can see some light with the bent straw because
it has been reflected when it hits the top inside edge of the straw. They will probably use the
term bend rather than reflect, but they may describe the concept of reflection. They may also
note that the light is not as bright with the bent straw as it is with the straight straw (when light is
traveling in a straight line through the straw). The conclusion should be that light can find its
way around things that it strikes, and thus it can bend.
Task-Specific Assessment Notes
Novice
The student has little understanding of the inquiry process and does not complete the
investigation. The student’s work does not lead the reader to know what s/he did or was
attempting to do. For example, the student uses the word brank at the first drawing but does not
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
5 of 12
indicate what s/he is referring to. The student does not appear to have a strategy and makes
statements (for example, "Down here the light bends”) that show that s/he is unable to make an
observation that is consistent with what s/he is asked to attempt.
Apprentice
The student’s work shows that s/he understands the investigation well enough to carry it out.
S/he attempts to create an observation from the first illustration, but there is little evidence of
predictions relating to the question being tested. The student’s comments (for example, “This
one it is really bright on our eyes”) show some evidence that s/he understands that light that is
close will be bright, but s/he does not connect it to the fact that light travels in a straight line or
that the light through the bent straw is the same distance away. The student’s conclusion states
that you cannot see anything through the bent straw, even though s/he did not observe that
there was NO light – or that it was completely dark. (Perhaps the student was trying to seek the
actual light bulb instead of the light from the bulb.)
Practitioner
The student makes a prediction and labels it correctly so that the reader can understand his/her
thinking. The student’s work shows evidence of recorded data (e.g., “just the light”). The student
states a conclusion (“Yes, because you put a lens in front of it”), but it lacks labels. The reader
has to infer that the student's conclusion is that light will bend in circles, since that conclusion is
not completely stated. This is a good opportunity for the teacher to question the student further
to assure a more complete response.
Expert
The student has a sense of how to apply the scientific method. The student’s process skills are
evident, and s/he has clearly recorded observations and predictions throughout the task. The
conclusion is clearly labeled, as are the observations and prediction. The student’s statements
show conceptual understandings about light.
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
6 of 12
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
7 of 12
Novice
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
8 of 12
Apprentice
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
9 of 12
Apprentice
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
10 of 12
Practitioner
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
11 of 12
Expert
Does Light Bend?
Copyright 2007, Exemplars, Inc. All rights reserved.
12 of 12