AlgoTutor Tutorial (4)

Using the Virtual Machine Component of AlgoTutor

J. Yoo, S. Yoo, C. Pettey, S. Seo, and Z. Dong

MTSU Computer Science Department

What is the Virtual Machine?

• The Virtual Machine is a component of the AlgoTutor System

• It allows you to visualize the flow of data through an algorithm

• To use the Virtual Machine, you need to first develop an algorithm for a given problem

• The Virtual Machine is only available for certain problems

How to use the Virtual Machine

• Start with an AlgoTutor problem exercise that has been created for the Virtual Machine.

• Solve the AlgoTutor problem (hint: the ordering and mapping phases are combined into one phase)– Drag Operations into the appropriate order– Click “compare my ordering w/ teacher’s” if you really need help but your grade is penalized if you do this too many times. Also, this only checks the ordering. It does not check the mapping.

– Click the variables tab to do the mapping

• Click “save changes”

How to use the Virtual Machine (continued)• Before clicking “Submit for grading” use the Virtual Machine to “trace” the flow of your algorithm– Use drop down arrows to select input– Click Trace execution (if the tracer window doesn’t show up check to see if you need to enable popups)

– Click Execute next step to see the result of each step

• Click “execute w/ selected” to see what would be output by the algorithm with the selected input

• Click “execute w/ all” to see the grade for your algorithm

• Click “Submit for grading” when you are happy with your grade

Select a lab

Select an Exercise that has been created for the Virtual Machine

Clickthe

Solvebutton

Notice the operationsphase and the mapping phaseare merged into

one phase

Begin as you would any other AlgoTutor problem

by draggingoperations from the right to the

left.

You can click the Compare my ordering w/ teacher’s button if you need help. Butdon’t click too many times or it will hurtyour grade. Also, only your ordering

will be compared. The mapping is not checked.

It does warn you howmany free checks youhave left before your

grade is hurt!!

When you are comfortablewith your ordering you

can do the mapping andthen use the tracer tocheck the mapping

There is no separatemapping phase.

You must click the Variables tab

to see the variables

Be sure to click thesave changesbutton before

using the virtual machinealgorithm tracer

Now you are ready totrace your algorithm.Begin by selectingyour input values.

Then click the Trace execution

button.If the tracer window

doesn’t show up,make sure you have

enabled popups.

Click the Execute the next step

button to seeeach step of your

algorithm

Valuesfor

variablesshow up

here

algorithm output is here

You can also just see whatwould be output by youralgorithm by selecting

input and thenclicking the

Execute w/ selectedbutton

Or you can click theExecute w/ allbutton to see

what your gradewould be

Note: Execute All takesa few seconds

to complete

Only when you are satisfied shouldyou click the

Submit for gradingbutton. You cannot goback and redo anything

once that button isclicked

You can changeyour mind about

submittingby clicking

Cancel

ClickView Solution

to seethe finishedalgorithm

Now you can do the next exercise in the

lab!!!