Cuesta College, San Luis Obispo, CA
[20 points.] An astronomy question on an online discussion board(*) was asked and answered:
Kory: When [is the Big Dipper] visible [for an observer] in the [n]orthern [h]emisphere?Discuss whether or not this answer is correct, and how you know this. Support your answer using a diagram showing the positions of the sun, moon, Earth, and an observer on Earth.
Tina L: [T]he [B]ig [D]ipper is highest in the early evening in the spring.
Solution and grading rubric:
- p = 20/20:
Correct. Clearly explains how the Big Dipper cannot be highest in the early evening spring sky. Specifically chooses a plausible "spring" month and "early evening" time on the starwheel and finds position of the Big Dipper is not very near the zenith, or instead places the Big Dipper near zenith, and finds that a plausible "spring" month cannot line up with an "early evening" time. Or may stretch the boundaries of "spring" months or "early evening" times to find Big Dipper near zenith, making this plausible.
- r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. May indicate when the Big Dipper is highest during a non-spring, non-early evening date/time instead.
- t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. Argument based on the Big Dipper being a circumpolar constellation, such that would be visible during any night of the year, but does not address plausibility of "highest in the early evening in the spring" statement. Or vague description of "spring" months or "early evening" times, or specifies date/time such that the Big Dipper is actually at lowest point in sky.
- v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Substantive discussion, but missing/problematic diagram.
- x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. Uses starwheel, but reports
inconsistent/incomplete date/time/position information.
- y = 2/20:
Irrelevant discussion/effectively blank.
- z = 0/20:
Exam code: midterm01s0Be
p: 16 students
r: 3 students
t: 12 students
v: 10 students
x: 0 students
y: 0 students
z: 1 student
A sample "p" response (from student 1449):
Another sample "p" response (from student 1339):