Use WITH Investigation 4, Part 2, Step 2

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1 INVESTIGATION 4 : The Sundial Project Use WITH Investigation 4, Part 2, Step 2 EALR 4: Earth and Space Science Big Idea: Earth in Space (ES1) Projects: Tether Ball Pole Sundial Globe and a Light Indoors Northern Hemisphere Sundial Core Content: Observing the Sun The Sun s Daily Motion 1 5/24/10 ad

2 TEACHER BACKGROUND Sundials on the Internet Finding True North in order to orientate the analemmatic sundial: The shadow of a pole perpendicular to the ground, or a suspended plum bob at solar noon will point true north. The above NOAA website will allow you to calculate solar noon for any given date, make sure you select if it is Daylight Savings time or not. Sun Time and Clock Time: Clock time for our time zone is set to 120. For each one degree difference there is a four minute change in time. In Vancouver, Longitude 122.6, the shadow will run "slow" ten minutes + the equation of time difference Analemmatic Dials: These sundials are not very common. They are unusual because the gnomon is vertical and the hours are marked not by lines but by points falling on the circumference of an ellipse. The gnomon has to be moved depending on the time of year, so that the shadow falls on the correct point. Analemmatic Dials are particularly suitable for sundials laid out on lawns, where a person can act as a gnomon; the position where the person should stand at any given month of the year is marked out along the north-south axis which crosses the mid-point between the foci of the ellipse. 2

3 STANDARDS Students learn that some of the objects they see in the sky change from minute to minute, while other things can be seen to follow patterns of movement if observed carefully over time. In grades 2-3 students learn that carefully observing and recording shadows provides an excellent way to trace the daily movement of the sun through the sky, which extends their observational skills. In later years, students will use this knowledge to realize that the Sun s apparent movement reflects Earth s daily spin on its axis. EALR 4: Earth and Space Science Content Standards Students know that: K-1 ES1B The position of the Sun in the sky appears to change during the day. 2-3 ES1A Outdoor shadows are longest during the morning and evening and shortest during the middle of the day. These changes in the length and direction of an object s shadow indicate the changing position of the Sun during the day. Performance Expectations Students are expected to: Compare the position of the Sun in the sky in the morning with its position in the sky at midday and in the afternoon. Mark the position of shadows cast by a stick over the course of a few hours and infer how the Sun has moved during that time. Observe that the length of shadows is shortest at about noon and infer that this is because the Sun is highest in the sky (but not directly overhead) at about that time. Explain how shadows could be used to tell the time of day. Big Idea: Earth in Space (ES1) Core Content: Observing the Sun The Sun s Daily Motion. Word Bank compare patterns position infer 3

4 TETHER BALL POLE SUNDIAL 2-3 ES1A Tools help scientists see more, measure more accurately and do things that they could not otherwise accomplish. Select appropriate tools and materials to meet a goal or solve a specific problem (e.g. Build the tallest tower with wooden blocks or the longest bridge span) and explain the reason for those choices. Volume 3, p. 185 Tether ball Pole Sundial: - Sidewalk chalk - Measuring tape (25 feet or longer) Watch the weather report for a future sunny day for marking the shadow. Plan for being outside each hour (on the hour, if possible). The Fall and Spring Equinox are ideal times to conduct this activity. News reports will reinforce the concept of the first day of fall or spring. (The winter solstice would also work but is rarely sunny.) How do shadows change during the day and what does that tell us about the sun? 1. Pick a playground pole tether ball and trace the shadow each hour over the course of the school day. After each tracing have students predict where and how long the next shadow will be. Have students locate the position of the sun each time they mark the shadow. Students can record in their Science Notebook what is happening to the shadow and the position of the sun. 2. Acting like the Earth: Have the students form a circle around the tether ball pole. What is one way the earth moves? (Lead them toward rotation.) Position 1: facing the pole (sun) this time is noon (nose to noon) Position 2: sideways to the pole (sun) this time is sunset (clockwise turn) Position 3: facing away from the pole (sun) this is night (eyes closed) Position 4: Sideways to the pole (sun) this is sunrise Model rotation and stating the time, noon, sunset, night, sunrise, noon When the earth rotates completely we have one day 3. Orbiting: (Writing the names of the seasons on the ground ahead of time helps. Writing the cardinal directions, North, South, East and West is helpful, or have a compass.) At the same time the earth is rotating it is also orbiting the sun. Can you rotate and orbit at the same time? Rotate and orbit until you have traveled one quarter of the way around the circle. This is one season. If you continued to orbit until you got back to where you started it would be one year. 4. Tilting: The earth is also tilted (23 degrees) towards the North Star (Polaris). Have students tilt north as they stand in the circle. 4

5 2-3 INQB Investigate ME and MY SHADOW Watch the weather report for a future sunny day for marking shadows, plan for being able to go outside each hour. (On the hour if possible) How does my shadow change during the day and what does that tell us about the sun? Pick a point in the sun where a distinct shadow is cast by the students. Lay a tape measure in the direction that the students shadows are cast. Starting in the morning, measure your shadow each hour (or several times over the day). Students can also use non-standard measurements, such as links on a chain. After each measurement ask: How do you think your shadow will be different the next time we measure? Have students find the location of the sun each time they measure. Discussion: What caused your shadow to change over the day? What happened to the position of the sun in the sky each time? When was your shadow the longest? Shortest? 2-3 INQE Model A scientific investigation may include making and following a plan to accurately observe and describe objects, events and organisms; make and record measurements and predict outcomes. Models are useful for understanding systems that are too big, too small, or too dangerous to study directly. Work with other students to make and follow a plan to carry out a scientific investigation. Actions may include accurately observing and describing objects, events and organisms; measuring and recording data; and predicting outcomes. Globe and a Light Indoors Use a simple model to study a system. Explain how the model can be used to understand the system. Make an open space where a light can be placed in the middle of the room and a person can walk around the light with a globe. Copy and attach the direction and season signs to room walls. 1. Position the students in a circle around the light bulb (a low wattage light bulb will be less distracting.) Pass the globe from student to student around the circle, students can spin the globe to show a day each time the globe is passed. Keep the axis pointed towards the North sign, as the globe is passed. 2. State at a season position such as summer (axis towards the sun), winter, spring or fall. Stop the globe at each seasonal position to examine how the light falls on the globe. In the northern hemisphere summer, Antarctica is always shaded. At the Spring and Fall (the equinox) light falls on all parts of one side of the earth. Volume 3, p. 185 : - Sidewalk chalk - Measuring tape (25 feet or longer) Summer Talk Volume 3, p. 177 Globe and a Light Indoors: - Bare round light bulb (sun) - Globe - Signs: North, South, East, West and Spring, Summer, Fall, Winter 5

6 A NORTHERN HEMISPHERE SUNDIAL Volume 3, p ES1A Outdoor shadows are longest during the morning and evening and shortest during the middle of the day. These changes in the length and direction of an object s shadow indicate the changing position of the Sun during the day. Mark the position of shadows cast by a stick over the course of a few hours and infer how the Sun has moved during that time. Observe that the length of shadows is shortest at about noon and infer that this is because the Sun is highest in the sky (but not directly overhead) at about that time. Explain how shadows could be used to tell the time of day. Using the sundial template provided, make copies for each student or student pair. Card stock style paper will provide the pencil gnomon with more support than regular paper. html Preconceptions: How did people tell time before clocks were invented? Northern Hemisphere Sundial: - Sundial template - Scissors - Tape - Pencil 1. The earliest clocks were some form of a sundial. Let s see how sundial time compares to clock time. Follow the directions on the sundial template to build the sundial. (Teacher Note: You will fold the #3 flap at 45 degrees, because Vancouver Washington is very close to 45 degrees North Latitude.) 2. Discuss: Why do we need clocks? What do we measure with clocks? How are modern clocks different from sundials? 3. Plan to take the sundial out on a sunny day on the clock hour such as noon. Use the background information to discuss finding true north. Your sundial will read accurate for sun time if the gnomon is pointing true North. 4. Compare: Is sun time the same as clock time? 5. Challenge: Arrange all the sundials so they read exactly the same time. What do you notice about the gnomon on each sundial? 6

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