Teachers’ Guide for Tell Me Why. Tell Me How: Why Is
the Sky Blue?
Teachers’ Guide for
Tell Me Why, Tell Me How: Why Is the
Students will understand these
that light is a form of energy that travels as a wave
that the different wavelengths of light connect to the
colors we see
that the colors we see depend on how our eyes detect
that the gases in the atmosphere affect the light that
reaches Earth’s surface
that we see the sky as blue because of the way light is
build content vocabulary
identify important information
interpret graphic features in nonfiction text
identify cause-and-effect relationships
conduct simple experiments with filtered light and
The title of the book presents a focusing question for
inquiry-based learning. Students can attempt to predict the answer to the
question before reading. They can then identify important information to help
them answer the question as they read.
Previewing the table of contents gives students the
opportunity to notice that the heading of the last chapter repeats the title
question. This gives a strong clue about where students can find the key
information for answering the book’s central question. You may wish to ask
students why they would read the rest of the book if they know the most
important information will come at the end. Possible answers include: "to
build the background we need to understand that last chapter" or "to
learn information that may not answer the question but is still useful or
The boldfaced words connect to glossary definitions at the
back of the book. You may choose to preview the glossary with students before
reading. Content vocabulary words are also often explained directly in the text.
Tell students that they can often read ahead or reread to find such context
clues. Model doing this with the word
filament on page 7
(defined as the thin wire inside a lightbulb) or atmosphere on page 13 (defined
as a "kind of shell" of gases).
the book includes several diagrams, scientific
illustrations, and labeled pictures to help students make visual connections to
the scientific concepts and vocabulary. Preview pages 5, 6, 9, 13, 20, 23, and
24 with students before reading. Tell them that these pictures show them pieces
of information that are difficult to describe with text alone. Say that the
labels help make clear the different things that are shown in pictures and
diagrams. Point out that labeled diagrams can also help readers understand
vocabulary, such as the layers of the atmosphere on page 13 (the names of the
different layers are not defined in the glossary, making this diagram
particularly important). Encourage students to think about how these graphic
features help them as they read, supplying sticky notes for them to record their
thoughts. After reading, discuss students’ thoughts about the
Several of the scientific concepts that are described in the
text are challenging to understand, especially on an initial reading, and
especially for visual learners. Encourage students to monitor their reading.
Give them strategies to clarify their understandings, such as rereading, reading
ahead, or flagging what they simply don’t understand for later discussion
(they might flag these difficult parts with sticky notes or bookmarks). You
might model self-correcting your own understanding by saying that you had to
reread page 6 because you had trouble remembering the differences between atoms,
electrons, and photons. Say that you flagged this page to reread later and to
check the glossary definitions. After they read, ask what students did to
self-correct their own understandings of difficult vocabulary and concepts. Help
them with the concepts they could not understand on their own. For other
activities that may clarify understandings, see the "After Reading"
and "Extension Activities" sections of this lesson, below.
ELLs and some other students may need help understanding
certain idioms, similes, and vocabulary that this book uses. When possible,
share physical examples of some of the objects used in similes such as
"like a wiggly line" (page 5) and "an atom is like a building
block" (page 6). Use direct explanations, drawings, or gestures to explain
other challenging words and phrases, such as "two peaks on this wiggly
line" (page 5), "a beam of light" (page 7), "the
‘ceiling’ of the thermosphere" (page 15), and so on.
Conduct a visualization exercise to have students make
personal connections and generate questions that will help them engage with
their reading. Ask them to close their eyes and picture a clear, sunny day. What
color is the sky? Can they think of other times when it is not this color? Tell
them to imagine that the sun is starting to set. How is the sky starting to
change colors as the light decreases? After students open their eyes, ask if
this exercise put any questions in their heads. Why do they think the sky is a
certain color when it is clear? Do they have any questions about what happens to
the sky’s colors as the sun sets? Write students’ questions on the
board to revisit after they read the book.
If you haven’t already done so, preview challenging
content vocabulary with students before reading (as discussed in the "Text
Supports" section of this lesson, above). Also preview the photographs and
diagrams in the book and ask students how they think these will relate to the
book’s title question (tell students that this may be difficult to see
before reading, and that it’s okay to make the best guesses they can at
Provide students with sticky notes to record additional
questions and facts that they learn as they read. Say that you will discuss what
they write down after they read.
Discuss student predictions to the answer to the title
question, as noted in the "Text Supports" section of this
Review any predictions students made before reading about
why the sky is blue. Ask students what they learned from the book that they
Remind students of the title question: "Why is the sky
blue?" Ask students to work in pairs to review the facts that they recorded
while reading. Which facts are most useful for answering the book’s main
question? Where are most of these facts found? Guide students to recognize that
the answer to the central question is answered most directly in the last chapter
and that the rest of the book mostly provides background to understand this last
Review pages 20 and 21 with students. Ask if the information
about the greenhouse effect and how light affects bone growth seems important.
Ask if these discussions answer the question "Why is the sky blue?"
Help students see that these topics may be interesting, but are less important
to understanding the book’s focus question.
Review any questions students flagged while reading. Ask
students if the book answered their questions, and if it didn’t where they
might look for additional information.
Clarify any challenging vocabulary or concepts that students
could not figure out on their own. Discuss the central scientific concepts,
including the fact that light is a form of energy that travels as a wave (pages
5–7), that the different wavelengths of light connect to the colors we see
and that the colors we see depend on how our eyes detect light (pages
8–11), that the gases in the atmosphere affect the light that reaches
Earth’s surface (pages 13–14 and 18–19), and that we see the
sky as blue because of the way light is scattered (pages 23–26).
Have students work in pairs to review the book for mentions
of cause-and-effect relationships. They can fold a sheet of paper in half down
its center line and record causes on one side and effects on the other. After
recording causes and effects from the book, they would then be able to fold one
half back and check that they could remember which cause went with which effect
(and vice versa). To locate the causes and effects within the book, suggest that
they look for key words, such as
example, the word
a cause and effect on page 7. Also note that some causes and effects will not
use these key words directly. Tell students that questions with answers can also
sometimes show cause-and-effect relationships. If students need guidance, model
writing out the cause and effect for the question and answer on page 9:
"humans can’t see most colors" (cause); "we can’t
count the wavelengths in light" (effect).
Provide students with flashlights, rubber bands, and sheets
of variously colored cellophane wrap (the cellophane can often be bought from
art supply stores or even stores that sell wrapping paper, but if this is
unavailable, sunglasses with colored lenses may be used instead). Have students
experiment with wrapping different colored cellophane around the lights and
shining the lights on a blank white background. Can they explain what is
happening to the light as it passes through the cellophane? Have them predict
what will happen to the light when they cover a flashlight with red, green, and
blue cellophane filters all at once. Will the light be totally shut out? If
light gets through, will it be a color? Have students do Internet research on
sites such as this
one or this
one that explain colored filters and use them in other activities.
Encourage them to connect their experiments and research with what the book said
about different colors of light having different wavelengths. If the filters let
through certain colors of light, which colors do they block?
See pages 27–28 of the book for an activity that
involves scattering light through a fish tank to show how different wavelengths
of light create different colors.