OBJECTIVES:

1.Learn how to identify where the Sun rises in Fremont.
2.Learn how to record and collect shadow data.
3.Students act as scientists by measuring shadows, recording the data, plotting the data and then interpreting why the shadows change its length.
 
VOCABULARY:
 
north, south, east, west
seasons (summer, fall/autumn, winter, spring)
horizon
shadow
 
MATERIALS: 
 
Shadow grid to collect data
Shadow line graph blanks and example
paperplate (9 inches)
Shadow stick (playdough and toothpick) to produce the shadow to measure
Data Sheet Summary 

 
BACKGROUND:
 
This long-term project helps students understand about the properties of light and what causes shadows. In their larger study of light, they will learn what causes day and night as well as what causes the seasons—why days get longer and shorter.
 
A shadow is an area where light from a light source is obstructed by an object. The shadow occupies all of the space behind an opaque object with light in front of it.
 
A year is the time it takes for the Earth to orbit the Sun once. As it orbits, the Earth has a tilt on its axis relative to the Sun, causing different seasons. Also, the tilt of the Earth's axis causes the angle of the sun (its apparent height in the sky) to differ during the year. This angle difference causes a change in the length of shadows. Low angles create longer shadows and high angles produce shorter shadows.
 
For the northern hemisphere, summer is when the northern hemisphere is tilted toward the Sun and winter is when it is tilted away from the sun.  The days are longer and the shadows are shorter in summer. Conversely, the days are shorter and the shadows are longer in winter. 
 
 
PROCEDURES:
1. The teacher needs to find a place on the playground that can be sunny at the time the class will take the reading. (Note: Due to shadows from trees and buildings, an ideal place at 10am may not be an ideal place at 1pm. Be sure to check the shadows at the time students will be taking measurements. Remember to adjust for Daylight Savings time in November and March).  Children should be facing East  (Mission Peak at Mattos)
 
2. Each student will measure shadows and record shadow length on a shadow grid.  If it is rainy or overcast, delay the reading until the next sunny day that works.
 
It is important that the cards are aligned similarly for each reading toward east.   Students should be facing where Sun is rising, so they do not get in way of the shadow.
 
They will write the date next to the mark. 
 
3.  The Shadow Grid already has concentric lines that are 1 cm apart and will make it easy for students to measure. 
 
4. Measurements should be taken bimonthly where possible. Teachers will decide whether measurements will be taken in centimeters or inches (we recommend centimeters).  You can collect data, put it in students folder and you may want to collect data on graph periodically.
 
5. At the end of the project, information from the Data Sheet Summaries will be used to make a line or bar graph for the year showing the changes in shadow length from month to month.
 
6. Ask students what patterns they see in the graph. Which months had longer shadows? Which months had shorter ones? Review why shadow length changes throughout the year in terms of the earth’s tilt relative to the Sun.