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A Platform that Integrates Quizzes into Videos
Robin Woll, Sven Buschbeck, Tino Steffens, Pascal Berrang, Jörn Loviscach
For reasons of wide access, privacy, and embeddability,
the platform does not require learners to regis-ter and
log in. In addition, by default no personal data of users
are saved on the servers; server-side statistics are only
stored cumulatively so that one can compute the mean
and the standard deviation of parameters over all users.
To gain insight into existing models for the use of quizzes
and the interaction with them, we looked at existing related
solutions. Among the major MOOC providers, Udacity
comes closest to the look of our plat-form, as it often uses
the final image of a video as a backdrop for HTML radio
buttons, checkboxes and text input fields in an ensuing
quiz. Outside the MOOCs sphere, there are several solutions
to create rigidly tem-platized quizzes, such as You-
Tube’s Video Questions Beta, educanon.com, ed.ted.com,
zaption.com, and the video editor that is part of the screen
recording software TechSmith Camtasia. The latter is also
noteworthy be-cause the generated Flash files (which admittedly
represent an outdated format) can communicate
the quiz re-sults to a learning management system using
the SCORM standard. This type of data transfer is of future
inter-est for embeddable learning objects served by
our platform. In a similar vein, the huge range of “multimedia”
quiz types offered by learningapps.org comes close to
our aim of embeddable units. Further inspiration stems
from HTML5 animation editors such as Adobe Edge Animate,
Google Web Designer, Mozilla PopcornMaker, and
Tumult Hype.
Functions of our Platform
Given that the videos we want to equip with quizzes
are hosted on YouTube, the obvious solution for putting
quizzes as layers on to top of the videos was to use the
YouTube API in combination with CSS3 to control which
element is placed on which layer. We wanted to keep the
design and structure of the quizzes as flexible as possible,
so they are encoded in plain HTML. This provides the quiz
author with a rich functionality. For in-stance, CSS3 allows
defining animations, which are frowned upon by many, but
– when used judiciously – can for instance counteract the
change blindness that occurs when a small text field is displayed
for the user to enter the result of computation that
is going on in the video, see Figure 1. Other HTML elements
include lines such as those shown in Figure 2.
Figure 1. The quiz asks the user to complete a computation before
the lecturer does so.
Figure 2. This quiz draws four lines as HTML code over the video.
The user is asked to click on the one with the specified slope.
As we are focusing on mathematics and related subjects,
we found it helpful to also build a domain specific lan-guage
(DSL) to evaluate a string entered by the user in a text field
as a symbolic mathematical expression. This enables the
author to create much deeper tests. Our DSL is basically a
Java port of an interpreter for Standard ML, a functional
programming language. We use this interpreter to parse
strings consisting of mathematical expressions. In addition,
it possesses much syntactic sugar to get closer to the
mathematical syntax that students are used to.
The author enters the expected answer as an expression
in the editor, say (a+b)^2. If the user types in a²+2ab+b²
instead of that (with superscript ² for the square and no
asterisk * for the multiplication), our DSL can assert that
those expressions are semantically equivalent. Furthermore,
the DSL can also check for a lower-level match, that
is, whether or not the user has simplified an expression to
the fullest extent. In this mode, the DSL for instance finds
that a(b+c) is equivalent to (b+c)a, but not to ab+ac, since
this would require a transformation of higher order.
Our focus on mathematics also led to the decision to
support LaTeX. For this purpose we integrated Math-
Jax since it supports a clean rendering of equations in all
modern browsers. Hence, the system can render complex
mathematical expressions on top of any video, see Figure
3. We expect the quiz authors to be familiar with basic La-
TeX syntax.
Research Track |156