Tutorial: Moodle VPL Min of 3 -- Python
--D. Thiebaut (talk) 17:13, 10 June 2014 (EDT)
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This tutorial builds up on the first tutorial of the series. Make sure you go through it before trying this one. In this tutorial we setup a VPL activity to test student Python programs that must input 3 numbers from the keyboard and output the smallest of the 3.
Setup
- Moodle Version 2.7 + (Build: 20140529)
- VPL Version 3.0.1
- For details on how Moodle and VPL were installed, go to this page.
Step-By-Step
- Log in as the instructor for the course on Moodle
- Create a new VPL activity
- 1 file max, set submission period, individual work, Grade of type point, 100 max, set category if necessary, Save and Display
- Create new Test cases:
case = Test 1 input = 3 5 10 output = 3.0 case = Test 2 input = 3 3 3 output = 3.0 case = Test 3 input = 1000 -1000 2000 output = -1000.0
- Execution Options: Run: Yes, Debug: No, Evaluate: Yes, Evaluate just on submission: No, Automatic Grade: Yes.
- Requested files: minOf3.py
- Execution files: do not touch any of them. Only the vpl_evaluate.cases will have some contents.
- Files to keep when running: Nothing checked.
- Test activity: enter a program that correctly returns the smallest of three numbers:
def main():
x = float( input( "> " ) )
y = float( input( "> " ) )
z = float( input( "> " ) )
print( min( [x, y, z] ) )
main()
- Save the program
Correct-Program Test
- Try the Run and Evaluate options and verify that the program passes the 3 tests:
The student's program passes all 3 tests and the program gets a grade of 100/100.
Faulty-Program Test
- Edit the program and introduce a logical error
def main(): x = float( input( "> " ) ) y = float( input( "> " ) ) z = float( input( "> " ) ) print( min( [x, x, z] ) ) # ERROR: y missing from list main()
- Evaluate the program
The student's program passes only 2 of the 3 tests and the program gets a grade of 66.67/100.
Testing a Program with a Syntax Error
- Edit the program and introduce a syntax error
def main(): x = float( input( "> " ) ) y = float( input( "> " ) ) z = float( input( "> " ) ) print( min( [x, y, z] ) # ERROR: right ) missing main()
- Evaluate the program
The student's program crashes the first test, but still manages to get an erroneous score of 66.67/100.
Improved Grading
To correct this inconsistency, we need to modify the test cases and assign some grade reduction to each test. The new vpl_evaouate.cases looks like this:
case = Test 1
grade reduction = 5%
input = 3
5
10
output = 3.0
case = Test 2
grade reduction = 10%
input = 3
3
3
output = 3.0
case = Test 3
grade reduction = 85%
input = 1000
-1000
2000
output = -1000.0
This is better, but we can improved the grading some more if we really wanted students to remove all syntax errors by assigning a grade reduction of 100% to each of the 3 tests.
100%-Off for Any Failed Test
Here is the revised vpl_evaluate.cases file:
case = Test 1
grade reduction = 100%
input = 3
5
10
output = 3.0
case = Test 2
grade reduction = 100%
input = 3
3
3
output = 3.0
case = Test 3
grade reduction = 100%
input = 1000
-1000
2000
output = -1000.0
And here is the result of the evaluation with the program that is missing a right parenthesis:
We note that the score is now 0/100 for the program that contains a syntax error and cannot pass any of the tests. Unfortunately the message displayed (" 3 tests run/ 1 test failed ") is still not correct.
This concludes this tutorial
