Numbas: open source e-assessment system

I have recently rewritten many of the questions from the Essential Maths for Medics and Vets modules using Numbas – an open e-assessment system and this post is about my experiences of using Numbas. I am not a mathematician and not a programmer (though I have done a little programming in the past) – my background is in biological chemistry and I have taught maths for first year biologists, medics, vets and psychology students at the University of Cambridge. The maths questions cover the techniques and concepts that beginning undergraduate students need in physiology, biochemistry, pharmacology and pathology. From what I can tell many of the questions are useful for non-medical biologists too.

What is Numbas?

“Numbas is a web-based e-assessment system that helps users create online tests. It was designed with numerical tests in mind, but is equally suitable for a range of other subjects. … We have created Numbas to be a valuable resource for educators, regardless of their budget. This is why the system is free and open-source, meaning that anyone can edit or adapt it to their needs.

Educators can set up a free account and choose from a public database of questions, or start creating their own. When they have put together their test, they can share it to places where students are already learning. Exams can be shared to a wide variety of locations, online and offline, and can be viewed on tablet, mobile or desktop.[1]


One of the most powerful aspects of Numbas is that you can create variables that change each time a student views the question so they can attempt the question as many times as they like. For example in the following question, the numbers change randomly (within a predetermined range).

(click on the image to enlarge)


And if the student clicks on “Reveal Answer” then can get advice that is tailored to the particular instance of the question:



Randomisation works well sometimes – but not others.

For questions like the one above this works well but for more specific scenarios such as the question below it becomes a lot more difficult.


The tutorials get you up to speed pretty quickly and writing simple questions like these with a few variables was possible after viewing a couple of short videos and reading the documentation.

LaTeX and JME

However…   getting the equations to look good requires the use of LaTeX and this is well known to have a pretty steep learning curve but there is plenty of online help – even a tool that allows you to write a mathematical expression by hand and it displays the LaTeX. Compare the following question display


With the LaTeX


In my opinion setting out the equations clearly is really important, especially for dyslexic or dyspraxic students and particularly for things like fractions and exponents, so LaTeX is really worth learning. The other thing that’s important for this group is font choice. It’s worth noting that any text written within the $ signs that designate the LaTeX input has Times New Roman as its default font. So when you want to include units in with an equation or some variables you need to either put them after the final $ or use the instruction \text to tell LaTeX to display as text rather than as mathematics. I decided in the end that I wanted the numbers to display in Times New Roman so that a one (1) wouldn’t look like an ell (l) but that the prefixes and units would be in the default web font (usually calibri). And whilst on the subject of prefixes, it’s worth knowing that to get a micro sign on a webpage you can go to a website called and type in the LaTeX code for the symbol, in this case \mu and it’ll display the Unicode symbol which you can then copy and paste into Numbas. This is the way of ensuring that the micro displays correctly.

Re-using and copying questions

In my view, one of the most powerful aspects of the Numbas system is the potential to copy, modify and/or re-use someone else’s questions. The first time I did this was when I was trying to figure out how to display standard form. I found a question by Martin Jones (thank you Martin!) and copied it, had a look at how he’d put it together, and then shamelessly created a similar question for myself using the same approach. It’s been quite handy being able to look at other people’s questions – sometimes to just copy and adapt but other times to see how they actually implemented it and to get other ideas for ways of presenting the info or asking the question.

Requiring a student to input their answer in standard form rather than just in scientific notation (i.e. as 1.3 x 106 rather than 13 x 105 or 130 x 104) turned out to be somewhat challenging. Of course 1.3 x 106 is equal to 13 x 105 so the Numbas system considers them the same as it should do. There were occasions when I particularly wanted the answer in standard form.  However with thanks to Christian Perfect, the Numbas developer, the problem was solved. I kicked myself when I saw Christian’s solution as I really should have thought of that myself. If you’re interested in the details, have a look at Christian’s version of my question

Another reason for copying someone else’s question is to add your own context. Because my students are primarily biomedical many of my questions have a biomedical context, so I ask for the concentration of adrenaline solution and express the answer with an appropriate unit or in standard form but it would be very easy to just copy my question and then modify the text to suit whichever field you’re in.

Sharing and Re-using

All of the Essential Maths for Medics and Vets are creative commons licensed (attribution, non-commercial, share-alike – see To download the question sets just go to the following link, select the question set you’re interested in (they have the tick icon in front) and choose which download option works best for you.

This link also contains the original audiovisual tutorials and pdf documents and you can link to this so students can revise the material before and/or after attempting the questions.

Alternatively you can create your own exams by putting together a selection of questions – either ones you’ve created yourself of copies you’ve made of other questions. Questions are generally tagged with keywords so you can find them.


To Christian Perfect and Bill Foster at Newcastle University for their prompt and helpful responses to my queries

To everyone who tested the questions and provided feedback: Nigel Atkins, Kingston University; Rebecca Barnes, University of Sheffield; Chrystalla Ferrier, Westminster University; Dawn Hawkins, Anglia Ruskin University; Robert Jenkins, University of Sheffield; Bernadette Leckenby, Sunderland University; Gemma Marsden, University of Northampton; Rosanne Quinnell, University of Sydney; Lois Rolling, University of East London; Felicity Savage, Anglia Ruskin University.




About JennyAKoenig

I specialise in science education and communication. Projects have included maths education for bioscientists, study skills for scientists with specific learning difficulties and pharmacology: bringing the science behind how medicines work (or don't!) to a wider audience. I have a PhD in Pharmacology from the University of Cambridge and a BSc (Hons 1) from the University of Sydney. Until Sept 2015 I divided my time between my science education and communication consultancy Science ETC (see and teaching at Lucy Cavendish College (where I was a Fellow). I am now a secondary science and maths teacher.
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2 Responses to Numbas: open source e-assessment system

  1. Hi Jenny,

    I have embedded the Essential Maths for Biologists, Medics and Vets page into our Moodle with some simple use of HTML. Do you think it is worth changing over to Numbas? It sounds like quite a bit of work, but I am not quite sure if there is much added benefit?

  2. JennyAKoenig says:

    Hi Nieky – I think those questions had got so old that they weren’t displaying properly in all browsers anymore so it had got to the point where something had to be done. Also the old site’s server is going to be switched off and moving them as they were was not going to be feasible I think. I think the new questions are a lot better in that you can generate lots of instances of essentially the same question (just with different numbers) and I think some students will like that. Also the feedback is a lot better. I think if you’re going to be writing lots of questions like that where you want to generate lots of instances then it’s worth it because you write just one question and generate lots of questions. Hope this helps!

    best wishes

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