(Chapter 8 lecture material is in a separate Web file and different overheads)
Exam 2
Overall Average: 53 (out of 100)
Part I (short answers): 25 (out of 40)
Part II (multiple choice): 14 (out of 30 questions)
score is part I + two times part II
Distribution of Scores
90'1 (1) x
80's (7) xxxx
70's (17) xxxxxxxx
60's (39) xxxxxxxxxxxxxxxxxxxx
50's (42) xxxxxxxxxxxxxxxxxxxxxx
40's (37) xxxxxxxxxxxxxxxxxxx
30's (24) xxxxxxxxxxxx
20' (12) xxxxxx
Look at the syllabus and grading policy
Exams 1,2, 3 = 100 points = 300 total
Final = 175 points
Paper = 75 points
All other contributions (50-100 ? .... assume 75 points)
total is 625 points
completed: 210 points
So, formally, it is possible to do well even if exams 1-2 was disaster
Paper is likely to have grades of 75-100%, can avoid 40-60%
(In practice, doing better isn't simple-- just because opportunity exists)
More important: how would I do better on next 2 exams?
Let's look at several grading styles
1. Preset grading pattern
A= 92%, B= 85% etc.
assumes level of questions, grading matches the scale
simplest pattern
often fine, if the instructor has recent experience
or relies on standard exam bank, previously standardized
can go astray as one changes book, exam style, etc.
could lead to 50% of class failing if narrowly applied I will not do this !
2. Straight Curve
10% A's, 20% are B's, 55% are C's, 10% are D's, 5% F's
give A's and D's based solely on relative standing
pure competition between students
I don't do straight curves (I think it's a bad idea)
Looking at a curve will show instructor troubles with exam scales
3. Relaxed (Sliding) Grade Scale
if grades look bad, might make ad hoc adjustments
add points or use a multiplier, but stick to the scale
try to adjust partially back to a normal curve
modified curve
some mechanical concerns
avoid skewing importance of any particular exam
4. Another grading tool, strategy
{EXAMPLE ONLY}
look at top 5 papers (perhaps skip top 2, average next 5)
take this as a starting point for a grading scale
exam 2 -- that's probably about 85
set A's as, say, 95% of that value (81-100)
set B's at 80-85% of that (72-80)
C's at 65% ( 51-71) ; passing at 50 or 55% (42-50)
Grading Changes in Midstream
different exam style
I don't like this approach since it introduces one new element of uncertanty and there's no opportunity to discover what the new style is like and how to adapt to it.
use other (more) graded assignments
rule based on best x out of y scores
extra credit work
Some recent suggestions:
study guide at the end of chapter, rather than before hour exam
specific sample problems, during study of a chapter
graded assignments, regularly
different use of class time-- less formal lecture
Some recent concerns
chapters too busy, complex-- hard to decide what to study
studied carefully, but didn't anticipate exam questions
knew the specific material, still answered wrong
some questions-- correct answers were too specific (judgment)
Some recent Observations
exam 1 vs. exam 2
exam 1 < 55 ..... generally held close on exam 2
exam 2 > 70 ..... average lower by 10, some by 20
drop is mainly on the multiple choice part
Questions with class scores <50%
(the numbering refers to form A, the version posted on the Web site)
question number, correct %, (most common incorrect response)
others had more correct answers than any other, but distributed
1 (33%) Ethanol in fuel
(important policy issue; textbook)
2 (38%) Formula of Hexane
(count bonds)
4 (20%) heat of Combustion of hydrogen
(hardest: need to compute)
5 (25%) dominant energy source
(emphasis in textbook)
8 (35%) BG and nitrate/nitrite
(lecture notes)
14 (48%) which species has polar covalent bonds
(lecture, book, role of water)
17 (37%) Beta radiation is ...
(fact to know, text and notes)
18 45% half life of radioactive material
(text and notes)
19 45% control rods in a reactor
(text, notes; reactors are a major focus)
21 33% NIMBY Not in My Back Yard)
(text, related to serious problems)
more b (incorrect) than e
22 20% Nuclear Depository
(text, notes-- perhaps largest problem in nuclear energy today)