New Augmented Reality Applications - Teaching through Multi-User Virtual Environments - page 380

The most structurally simple silicates involve
isolated tetrahedrons. The zircon (ZrSiO4), de-
scribed above, is one of the most famous examples
(see Figure 8b). These silicates are called neso-
silicates (see Figure 8c). When there are two
isolated tetrahedrons sharing a common oxygen
atom, they are called sorosilicates, [Si 2 O 7 ] 6- (see
Figure 8d). Compounds of this subclass are formed
when cations are bounded to each double tetra-
hedron.
The cyclosilicates are rings that consist of three
or six tetrahedrons sharing oxygen atoms (see
Figure 8e). Their formula can be easily calculated
from their basic rings: [Si 3 O 9 ] 6- for the cyclosili-
cates of three tetrahedrons and [Si 6 O 18 ] 12- for the
cyclosilicates of six tetrahedrons. An example
of a cyclosilicate is the beryl, Be 3 Al 2 (SiO 3 ) 6 . Its
structure is based on layers of rings of tetrahedrons
(see Figure 8f).
When the tetrahedrons are arranged forming
chains, there are called inosilicates (see Figure
8h). They can be made of a single chain or a
double chain of tetrahedrons. The single chains
are pyroxenes and the double chains, amphiboles.
The formula is [Si n O 3n ] 2n- for pyroxenes and
[Si 4n O 11n ] 6n− for amphiboles. These formulas may
be inferred from the structures.
Phyllosilicates consist of sheets of tetrahe-
drons (see Figure 8g). A two-dimensional layered
structure is produced by sharing three oxygen ions
with each of the tetrahedrons. For this structure
the repeating unit formula may be represented by
[Si n O 3n ] 2n- . When the tetrahedrons are arranged in
a 3D framework, sharing each oxygen atoms, they
are called tectosilicates.

We surveyed fifteen students randomly chosen
from the three classes Note that some of them were
in more than one class. Their general opinion was
that using AR to understand crystalline structures
was very useful. All of them said that AR was a
powerful tool that helped them understand the
3D arrangement of structures. Furthermore, most
of them (70%) wanted to use it at home on their
personal laptop or desktop computer.
40% of the students agreed that the main ad-
vantage of using AR in Inorganic Chemistry was
the possibility of interacting with the models by
moving and rotating the physical markers. This was
more intuitive than imagining the final structure
of a compound using two-dimensional figures and
pictures. Another 40% answered that the main
advantage was the option of easily analyzing the
crystalline structures from different angles and
directions. Finally, the remaining 20% said that
our system was very valuable in helping them
improve their visual and spatial skills.
As for the disadvantages, 50% of the students
complained about not having a physical system
permanently installed in the classroom. They want
a system with more webcams. They also want to
be able to faster set up the system at the beginning
of the class. Another 15% thought that the main
disadvantage was the small size of the images in
the projection screen. Finally, the remaining 35%
of the students did not see any disadvantage to
the system. They also recommended continuing
with the project and having the AR system further
improved.
Finally, we asked about adding stereo to the
system, and 95% of the students agreed that it
would be a good idea.

Students' Opinion

FUTURe ReSeARCH DIReCTIONS In order to know the students' opinion about our

AR system, we performed a survey in the three
classes. The goal was to find their opinions about
the advantages and disadvantages of the system.
We also wanted to know whether it was useful
or not.

In this Section, we explain possible ways to
continue and improve the work we are doing.
For that, we consider the opinions of the people