## Question types: Algebra

qtype_algebra

Maintained by Jean-Michel Védrine

Question type where the student must answer by typing an algebra formula. Correctness can be checked by three different methods.

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Moodle 2.3, 2.4, 2.5

MOODLE ALGEBRA QUESTION TYPE

Created by Roger Moore

Algebra based question type for Moodle.

This plugin implements an algebraic question type where student responses are treated as an algebraic expression and compared to instructor provided answers using the basic rules of algebra.

### Useful links

### Contributors

Jean-Michel Védrine (Lead maintainer)

Roger Moore: Original Author

Please login to view contributors details and/or to contact them

Debug info: Errors found in XMLDB file: Some TABLES previous/next values are incorrect

Error code: ddlxmlfileerror

Stack trace:

line 349 of \lib\ddl\database_manager.php: ddl_exception thrown

line 365 of \lib\ddl\database_manager.php: call to database_manager->load_xmldb_file()

line 436 of \lib\upgradelib.php: call to database_manager->install_from_xmldb_file()

line 1544 of \lib\upgradelib.php: call to upgrade_plugins()

line 349 of \admin\index.php: call to upgrade_noncore()

Thanks for the report,

Probably I made a mistake when doing "last minute changes" just before the release". Sorry for that. I will correct the problem and upload a new version.

I have created CONTRIB-4315 tracker issue to keep track of the problem and published a new corrected version (1.11). As I expected it was only a 1 word change.Stupid mistake and not well tested code from me. Sorry for the inconvenience.

Using the "algebra question type" I noticed, that some algebraic expressions entered by the user are translated in a strange way: entering "3 * 5" and checking the input by pressing the "display response" button leads to the output "3 times 5". This is very confusing when you enter large expressions. Is there an option to replace the word "times" by the point usually used für multiplications?

Another problem I am facing is, that you cannot enter a variable that is not used für calculating the right answer. My pupils are supposed to transform terms. Sometimes it happens, that a variable contained in the beginning term "dissapears" during the transformation. When the pupils enter this variable and press the "display response" button, an error message appears and they know, that their solution is wrong before they press "submit" and get points or not. A workaround is, to enter the variable in the solution multiplied by zero, but as the right solution is displayed in the end, this leads to confusion, too.

Example term: 3x-4x+y+x will be transformed to: y

Entering any expression containing x will produce an error ...

Have you the TeX filter or MathJax activated on your Moodle website ? I guess not because you should see a properly formatted response with a nice multiply sign rather than "times". I should make clear in the instructions that the algebra question type expect that there is a way to display TeX expressions activated for the display to work properly.

Your problem with variables would be quite complex to solve and would need huge changes in the code from the way it works now. As this question type was created by Roger Moore and I am only maintaining it so that it works with current Moodle versions, I don't expect to be able to make such changes in a foreseeable future. Sorry.

Maybe you should have a look at more complex math questions types like Stack or formulas to see if they better suit your needs ?

I use the current version with Moodle 2.6 and also Moodle 2.7beta and I have not seen any problem. Also nobody reported any bug so I think you are safe to use it with Moodle 2.6. If you see any bug or problem, create a tracker issue and I will work on it.

we are using the algebra question type on a Moodle 2.9 server, but we have a problem with the formula preview: We cannot make the TeX preview work with MathJax. MathJax is enabled and works everywhere else on the site, but the preview in the algebra questions remains raw TeX code. If we enable the old TeX filter, the formulas get converted to images, but it also breaks the displayed formulas in the rest of the site: All TeX is interpreted as inline math.

Do you have any idea, what might cause this and how to fix it?

I solved my problem described above. To fix the LaTeX preview of the algebra questions, I had to insert the line

into the "Within HEAD" section in the "Site administration > Appearance > Additional HTML" settings. Now the preview uses MathJax as it should.

Cheers

Lukas

The line should read:

[script type="text/javascript" src="https://cdn.mathjax.org/mathjax/2.5-latest/MathJax.js?config=TeX-AMS_HTML"][/script]

Just replace the square brackets with the angular html kind.