Exploring Daily Shadow Changes
Lesson 7 of 10
Objective: SWBAT explain how our shadows change throughout the day.
Inquiry Based Instructional Model
To intertwine scientific knowledge and practices and to empower students to learn through exploration, it is essential for scientific inquiry to be embedded in science education. While there are many types of inquiry-based models, one model that I've grown to appreciate and use is called the FERA Learning Cycle, developed by the National Science Resources Center (NSRC):
A framework for implementation can be found here.
I absolutely love how the Center for Inquiry Science at the Institute for Systems Biology explains that this is "not a locked-step method" but "rather a cyclical process," meaning that some lessons may start off at the focus phase while others may begin at the explore phase.
Finally, an amazing article found at Edudemic.com, How Inquiry-Based Learning Works with STEM, very clearly outlines how inquiry based learning "paves the way for effective learning in science" and supports College and Career Readiness, particularly in the area of STEM career choices.
In this unit, students begin by studying the location of the Earth in the Universe. Then, students learn about the brightness of stars through investigations and research. At the end of this unit, students explore the patterns on Earth, such as day/night and the length of shadows.
Summary of Lesson
Today, I open the lesson by introducing vocabulary and discussing cardinal directions. Students then explore how shadows change by measuring their shadows outside throughout the day and investigating with a marker and flashlight. At the end of the lesson, students reflect and apply their new understanding of changing shadows by constructing written explanations.
Next Generation Science Standards
This lesson will support the following NGSS Standard(s):
5-ESS1-2. Represent data in graphical displays to reveal patterns of daily changes in length and direction of shadows, day and night, and the seasonal appearance of some stars in the night sky.
Scientific & Engineering Practices
For this lesson, students are engaged in Science & Engineering Practice:
Science & Engineering Practice 3: Planning and Carrying out Investigations
Students conduct two shadow investigations today while attending to data collection, observations, and completing fair tests.
To relate ideas across disciplinary content, during this lesson I focus on the following Crosscutting Concept:
Crosscutting Concept 2: Cause and Effect
Students examine the cause and effect relationships between their shadows and the sun. Eventually, they determine that shadows are longer when the sun is closer to the horizon and shorter when the sun is higher in the sky.
Disciplinary Core Ideas
In addition, this lesson also aligns with the following Disciplinary Core Ideas:
ESS1.B: Earth and the Solar System
The orbits of Earth around the sun and of the moon around Earth, together with the rotation of Earth about an axis between its North and South poles, cause observable patterns. These include day and night; daily changes in the length and direction of shadows; and different positions of the sun, moon, and stars at different times of the day, month, and year. (5-ESS1-2)
To add depth to student understanding, when I can, I'll often integrate ELA standards with science lessons. Today, students will work on meeting CCSS.ELA-LITERACY.W.5.2: Write informative/explanatory texts to examine a topic and convey ideas and information clearly. After investigating shadows, students write an informative paragraph to convey their ideas.
Choosing Science Teams
With science, it is often difficult to find a balance between providing students with as many hands-on experiences as possible, having plenty of science materials, and offering students a collaborative setting to solve problems. Any time groups have four or more students, the opportunities for individual students to speak and take part in the exploration process decreases. With groups of two, I often struggle to find enough science materials to go around. So this year, I chose to place students in teams of two or three! Picking science teams is always easy as I already have students placed in desk groups based upon behavior, abilities, and communication skills. Each desk group has about six kids, so I simply divide this larger group in half or thirds.
Gathering Supplies & Assigning Roles
To encourage a smooth running classroom, I ask students to decide who is a 1, 2, or 3 in their groups of three students (without talking). In no time, each student has a number in the air. I'll then ask the "threes" to get certain supplies, "ones" to grab their computers, and "twos" to hand out papers (or whatever is needed for the lesson). This management strategy has proven to be effective when cleaning up and returning supplies as well!
Teacher Note: This lesson needs a sunny day as students go outside to trace their shadows!
Partners & Computers
During today's lesson, students will be working in teams of two students (elbow partners). Each team of students will have one laptop computer to share. While we have enough computers for all students, I have found that partners are more successful collaborators when they are sharing one device.
For the Sun and Earth's Patterns Unit, students are creating an envelope book to help organize new information and to support an inquiry approach during the learning process. Prior to the unit, I used a plastic comb binding machine (pictured below) to create envelope books using 10 envelopes for each student's book: Envelope Books. During today's lesson, students will be working with the seventh envelope in their books.
For each envelope, students are provided with up to 3 vocabulary cards: Vocabulary Cards (I copied these onto green card stock paper & cut each page into 10 cards): Vocabulary Cards. For easy distribution, I placed these cards into ziplock baggies so that each group of students could easily take cards out as needed: Vocabulary Cards in Bags. As an opening to the lesson, I write the following vocabulary words on the board: shadow, cardinal direction, intercardinal direction.
Students work together with their partners to discover the meaning of each word, using their computers and/or dictionaries as resources. As students are ready, they share definitions out loud with the rest of the class. We discuss student findings and then I construct a student-friendly definition (using student input) for all students to record on their cards. This process is important for two reasons: (1) sometimes students record definitions that are difficult to understand due to complex language and (2) this also allows students to see how important it is to use multiple sources when conducting research.
Here's an example of student vocabulary cards: Student Vocabulary Cards.
Making Vocabulary Meaningful
As we discuss the cardinal directions, I place the following labels on the four walls in our classroom: Cardinal Directions.
Teacher Note: Understanding cardinal and intercardinal directions will help student record the direction of their shadows today.
Also, I draw the following graphic on the board, Cardinal Directions & Intercardinal Directions, to help students differentiate between cardinal and intercardinal directions.
To help students apply their new understanding of directions, I ask students to stand up and face a certain direction. For example, I start by asking students to face north, then south, then east, then west. Then, I ask students to face northwest and northeast, as well as southwest and southeast. This really helps many of my students grasp these concepts!
Developing a Guiding Question
To support an inquiry-based learning model and Science & Engineering Practice 1 (Asking Questions and Defining Problems), I explain: Today, you will be learning about shadows. Think about the vocabulary words that we've discussed so far and think about what they have to do with shadows. What guiding question do you think we should research today? Student questions include:
- What effect does the sun in the sky have on where the shadows are pointed?
- How can Earth tell us where we're located?
- Do intercardinal directions and cardinal directions have to do with shadows?
- How do the four directions interact with shadows?
- How does the direction of the sun affect the shadows?
- When the sun moves, does it affect where the shadows are?
As students share their thinking, I'm hoping that with some teacher guidance, students will reflect upon the vocabulary words and ask, "How do our shadows change throughout the day?" Several students come up with a similar question to our guiding question.
Here's a video of this question-development process in action: Developing Guiding Question.
Lesson Introduction & Goal
Now that students have helped develop a guiding question, I introduce today's learning goal: I can explain how our shadows change throughout the day.
I continue on by passing out an envelope picture to each student: Envelope 7 Pictures. Pictures add an element of excitement to learning and they provide support for students who learn best using visual aids.
On the front cover of the seventh envelope in student envelope books, I model how to paste the picture and write the investigative question for today's lesson: How do our shadows change throughout the day? (Student Envelope Example).
Fact-Based Argument Cards
For each envelope, students are provided with a Fact-Based Argument Card: Fact-Based Argument Cards (I copied these onto yellow card stock paper & cut each paper into 3 cards: Argument Cards). As I pass this card out to each student, I explain: At the end of today's lesson, you will each have the opportunity to construct a fact-based argument, explaining how shadows change throughout the day. Remember, as scientists, it is important to make sure that your arguments and explanations are based on evidence and research findings!
Teacher Note: By asking students to develop explanations based upon evidence and research findings, I am supporting Science & Engineering Practice 7: Engaging in Argument from Evidence.
For this lesson, I want to provide students with a hands-on experience investigating how their shadows change throughout the day. To prepare, I set out the following for each group: a bag with a piece of sidewalk chalk (Bags of Chalk), a compass (Compasses), and meter sticks (Meter Sticks). I explain: Today, we will be going outside every hour to examine how our shadows change throughout the day.
I ask the students in each group of three to show me a 1, 2, or 3 on their hands. I then ask the #1 students to get a compass. You will be the person being traced today. You will also be in charge of determining the direction of the sun and the direction of your shadow.
I ask #2 students to get a bag with chalk. You will be in charge of tracing each of the shadows today.
I ask #3 students to get two meter sticks. You will be in charge of measuring the length of each shadow today.
I pass out a copy of Student Shadow Record Sheet to each student and explain: Today, you'll each be keeping track of the time, location of the sun, direction of the shadow, and the length of the shadow, measured to the nearest inch. One of the most important rules to remember today is: don't look directly at the sun as it can hurt your eyes.
I also went over the following key steps:
- Draw around the feet of the person casting a shadow and place his/her initials inside the feet. Each time you go outside today, the person will stand in the exact same spot. Here's what this will look like: Tracing Around Feet.
- Make sure to label each shadow with the time so that you can look back and make accurate observations. I draw a diagram on the board to ensure understanding: Labeling Shadows. Here's one group's labels: Student Labels on Shadows.
- Whenever we go outside, always start by tracing and measuring the shadow. If you don't get to the location of the sun and direction of the shadow, we will discuss these as a whole group.
At this point, we all gather outside to watch a group model the procedures: Student Group Modeling Procedures. This turns out to be very effective. All groups understood exactly what to do and were very successful throughout the rest of the day.
As students investigate, I conference with as many students as possible. Here, Students Making Observations, the students notice their shadow already getting shorter and changing directions!
During our second outing, this group notices the shadow getting shorter as well: Changing Shadows. Students are surprised at how quickly their shadows are changing! I'm reminded of how much students can learn just by observing the world around them.
Here's how each group's shadows changed over the course of first three hours: Shadows Getting Shorter.
Teacher Note: Originally, I had planned for students to begin measuring their shadows an hour earlier. However, after checking the conditions, I noticed that my shadow was so long that it extended over the snow and into the school building! Also, I should have asked students to spread out more. By the time we got to our fourth tracing, student shadows were running into each other and into the snow: Running out of Room!
Following each outing, we discuss the direction of shadows and the direction of the sun. Students added to or changed their notes on their Student Shadow Record Sheets. Here are a few examples of student notes during this time:
Rich conversations follow each outing as well. For example, one student points out, "Our shadows keep getting shorter and shorter." Why do you think that is? Another student shares, "The sun was down much lower this morning. Now the sun is up higher." What do you think is going to happen this evening? Is your shadow going to continue getting longer? Students agree, "The sun will get lower in the sky again, which means our shadows will get longer again." Here's an example of a student conference during this time: Student Pondering Shadow Length.
Making a Graph
Now that students have gathered data on their shadows, I pass out a copy of Student Shadow Graph (cut into half sheets) to each student. We begin by discussing an appropriate scale interval on the y-axis. Some students are able to count by 25 while others count by 30 in order to accommodate their highest data points.
Monitoring Student Understanding
Once students begin working, I conference with every group. My goal is to support students by asking guiding questions (listed below). I also want to encourage students to engage in Science & Engineering Practice 7: Engaging in Argument from Evidence.
- What patterns have you noticed?
- Why do you suppose ____?
- What have you found so far?
- Has your thinking changed?
- What evidence do you have?
- How did you decide _____?
- What conclusion can you draw about ____?
Having had experience with graphing during past lessons in this unit, it doesn't take students long to complete this task: Student Graphing & Making Predictions.
Here are a few examples of completed graphs:
Reflect & Apply
Marker & Flashlight Investigation
Before students reflect and apply on today's findings, I want students to explore how shadows change, depending on the angle of the the light source, using a flashlight and a marker (Marker & Flashlight Investigation). To prepare for this simple investigation, I set out enough Markers & Flashlights for each group of three students to have one marker and one flashlight. I provided minimal directions for this investigation. I simply encouraged students to experiment with the angle of of the flashlight: What happens if the flashlight is down low to the floor? What happens if the flashlight is directly above the marker? How does the shadow change?
While students investigate, I conference with as many groups as possible. Here, Students Investigating with Flashlights, a group uses their experiences outside to help explain the shadows cast by the marker.
Now that students have built meaning and understanding by observing, questioning, and exploring, it is important to provide students with the opportunity to apply their findings. For this reason, I invite students to use their research to answer the guiding question, "How do our shadows change throughout the day?" by writing a fact-based argument on one of their Fact-Based Argument Cards.
I remind students once more: Remember, as scientists, it is important to make sure that your arguments and explanations are always based on evidence and research findings!
As students begin to finish, I ask volunteers to share their arguments aloud. I also invite others to respectfully agree or disagree with other students' arguments as it is important for students to provide and receive critique from peers and to differentiate between arguments based on reasoned judgement and arguments based on research findings (Science & Engineering Practice 7: Engaging in Argument from Evidence).
Here, Student Sharing Argument, a student shares his argument, and I encourage him to strengthen his argument by adding exact evidence from his investigation.
To get students started, I provide the following writing prompt: Our shadows change throughout the day.
Here are a couple examples of Fact-Based Argument Cards during this time:
At the end of this lesson, students place the following items in today's envelope: