Students will be introduced to the concept of altitude by visualizing a 180 degree arc projected into the sky.
- Degrees (as a unit of measurement)
- Fixed object
- Solar noon
In the world of mathematics two types of measure are commonly used. Linear measure measures distances between two objects. If you've used a ruler you are familiar with linear measure. Angular measure is based on a circle of 360 degrees. For example, 90 degrees would be 1/4 of a circle.
- Move students to the playground and have them form in groups at the cardinal points of the compass rose. Have the students face north (using the compass rose and the reference point determined in Activity One).
- Have your students outstretch their hands so that they are pointing to north on the horizon. Lead your students in swinging their hands overhead to the zenith and on to the south point of the horizon (describing the arc of 180 degrees.) Have your students look at their recording devise from Activity Two and recognize that the arc they have just traced is the same as the one that they had created on paper.
- Have your students draw what is they see at the northern horizon, the zenith, and the southern horizon. Warn your students that they will not see a lot at the zenith.
Caution! Warn your students to never look directly at the sun!
Students should share and discuss their observations once you return to the classroom. They may identify fixed objects on their recording papers and compare them.
Students should answer the following questions in their journals and be prepared to discuss their answers in class.
- What systems of measurement do you use to measure positions on the earth? (Examples are miles, latitude, and longitude.)
- What words could you use to describe the position of the sun in relation to you?
- Is the sun ever at your zenith where you live?If no, why not?
- Can you imagine a system like longitude, latitude in the sky?
Help your students connect the ideas of longitude and latitude to the idea of altitude and azimuth by asking them the following questions.
- If you were standing at the equator, which is marked 0 degrees at the east and at the west, at which degree would you be able to correctly mark your zenith?
- How would you defend your reason for doing so?
- Using the altitude/azimuth system of measurement at what degree would the sun be at solar noon?
Have your students go outside at home tonight or on the first clear night and record what they see at their zenith in their journals. Have them record the date and the time, and discuss what they saw.
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