Question types: Electron Pushing / Curved Arrow

Maintained by Picture of Carl LeBlond Carl LeBlond
Curved Arrow / Electron Pushing question can be used to test and strengthen students knowledge of reaction mechanism, resonance and curved arrow notation. This plugin requires Marvin Applets from Chemaxon.
15 sites


Curved Arrow / Electron Pushing question can be used to test and strengthen students knowledge of reaction mechanism, resonance and curved arrow notation.  The instructor builds a reaction scheme/mechanism with all electron pushing arrows and the student must provide the correct arrows on the reaction during assessment.  Note:  This plugin requires MArvin Applets from Chemaxon
You can ask questions such as;
  • Please add curved arrows showing the flow of electrons for the following reaction?
  • Please add curved arrows showing how the following resonance structure could be obtained?


  • Interactive - students draw curved arrows representing flow of electrons.
  • Students can view step by step arrow placement.
  • Multistep reactions OK!
  • Radical or Polar reactions possible.
  • Teacher can hide or show products for varying difficulty.
  • Teacher can require strict arrow addition order.


This plugin adopts the same license that Moodle does.  The Marvin Applets are free for academic purposes.


This plugin was developed at the Indiana University of Pennsylvania (IUP).  Neither IUP or Carl LeBlond are affiliated with Chemaxon.


This plugin requires Marvin Applets from Chemaxon which can be downloaded here.  Download the full package and install it at your web servers root directory.


Example questions are provided as a Moodle xml file in the examples folder.

A video available here, outlines using this plugin.



This plugin is part of set EasyOChem.


Screenshot #0
Screenshot #1


Picture of Carl LeBlond
Carl LeBlond (Lead maintainer)
Please login to view contributors details and/or to contact them

Comments RSS

Show comments
  • Picture of Carl LeBlond
    Wed, 2 Apr 2014, 3:38 AM
    Anthony - I found some javascript on the edit form page and replaced with YUI calls. I should point out there is one other small bit of javascript thats called from renderer.php which handles showing students correct and incorrect answers. If this is an issue I can just delete that functionality so we can move forward. Updates are on github.

    Should I upload new version to everytime I make some changes to the code or should I wait till we are closer to approval?
  • Anthony Borrow
    Wed, 2 Apr 2014, 9:36 AM
    Carl - Go ahead and add the new version so that when it is approved it will have the latest and greatest code. Peace - Anthony
  • Anthony Borrow
    Wed, 2 Apr 2014, 9:38 AM
    p.s. - after adding the new zip file, under Administration, select the option to Schedule this plugin for re-approval
  • Anthony Borrow
    Wed, 9 Apr 2014, 10:21 AM

    Thanks for your continued work. I appreciated having the example questions to import. When previewing one of the questions, I saw the following PHP notice you may want to fix when you get a chance:

    Notice: Undefined property: stdClass::$qtype_easyomech_options in /var/www/m26/question/type/easyomech/renderer.php on line 149

    When I went to submit an answer I noticed:

    Fatal error: Call to a member function attributes() on a non-object in /var/www/m26/question/type/easyomech/question.php on line 49

    I also saw the question revealing technical information on the preview - I had not noticed that before on questions but figured I would share it with you in case it was disclosing information that it should not be. What I saw was:

    Behaviour being used: Deferred feedback

    Minimum fraction: 0

    Maximum fraction: 1

    Question summary: Provide curved arrows for the following reaction mechanism?

    Right answer summary: <?xml version="1.0" encoding="UTF-8"?>
    Question state: complete

    For now, I am going to mark this plugin as needing more work until we get these issues resolved. Thanks for your patience with the review and approval process. Peace - Anthony
  • Picture of Carl LeBlond
    Wed, 9 Apr 2014, 11:56 PM
    Anthony - I fixed the undefined property notice and the error. The fatal error occurred when a student attempted a question expecting radical arrows but did not add any arrows. Should be all good now. I submitted for re-approval. Thanks for catching that error!
  • Anthony Borrow
    Wed, 23 Apr 2014, 10:42 AM
    Carl - Many thanks for tidying things up. I am ready to approve this plugin. If you need anything else, just let me know. Peace - Anthony
  • Picture of Bren Denger
    Mon, 12 Dec 2016, 6:53 PM
    I wonder what questions I can make up using the plugin. I guess the ones used here could be easily found by the students, if I use them... I need something unique for Programming. I found some BuyEssayInfo of one company that can make a task on that. But they don't help with Moodle plugins. I think there should be some IT and programming oriented services that could do that.
    Can you please e-mail the questions? So that they should not be visible for the online users.
  • Picture of kat8adamson kat8adamson
    Fri, 24 Feb 2017, 7:31 PM
    Thanks for the sharing your post, and thank you guys for the useful links. I will share it with my friends who has their own website. Their writers have helped me with my paper. They cam use this plugin in their work.
  • Picture of jack reecher
    Mon, 11 Dec 2017, 5:11 PM
    Actually, this is my first visit here and I got lots of information about the electron pushing and related contents. I think many people are not aware of it. I will be grateful if you have shared more information.knowledgeable about
  • Picture of shiva moola
    Wed, 27 Dec 2017, 2:11 PM
    The SSLC Result 2018 Tamilnadu will be going to Release this May and all the students who are willing to know the official Tamilnadu SSLC Result would request to search on the official organization website
  • Picture of Kyle Swift
    Wed, 7 Feb 2018, 7:03 PM
    I can imagine that those used here can simply be originated by substitutes. I want approximately special for programming. I discovered a part of an organization that could work with. Assignment Writing Wherever they can, they will not help with the Moodle modules.
  • Picture of Laura Duncan
    Tue, 13 Feb 2018, 9:30 PM
    Good advice. It would also be great if you could recommend the best place where I can buy essays now. It's very important for me at the moment.
  • Picture of Kate Sommers
    Fri, 9 Mar 2018, 4:14 PM
    Pass the writing of your essay to [url=]quality essay at Paper Masters[/url]
  • Picture of Ashley Rosa
    Mon, 30 Apr 2018, 2:08 PM
    Thanks for sharing information, zoho mail sign up
1 2
Please login to post comments