Learning Across Sites: New tools, infrastructures and practices - Earli

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Intersecting trajectories of participation 115
The knowledge about DNA that the students are approaching has been developed
in the biological sciences over an extensive period of time and is considered
to be a complex problem area. The domain is presented for the students as given,
and the task they are asked to solve is presented as a straightforward school task
when they are requested to sequence a short part of the DNA molecule, the socalled
insulin gene. The DNA molecule of insulin gene consists of pairs of bases.
The bases are A (adenine) and T (thymine) that are always bound together, and
C (cytosine) and G (guanine) that are also linked. Because there is a regular relationship
between the base pairs, the scientific convention is that it is sufficient to
mention only one of the sides of the molecule while sequencing.
Sequencing the insulin gene requires starting to read from the bottom of
the gene and upwards to the top along one side. This entails that, according to
Figure 7.2, the students are expected to read: ‘ATG TTT . . .’ That is the column
on the right in Figure 7.2.
In the excerpt the students are expected to read the right- hand side of Figure 7.2.
As we will see further down, this has to do with how the knowledge domain is
inscribed in one of the technologies.
The insulin gene in Figure 7.2 has been made more authentic, when represented
as a computer- based 3D model that has been rotated.
The 3D model has been designed and placed at a fixed point in the learning
environment, and gives the students and their teacher the possibility to interact,
and manipulate the objects by picking them up and putting them down by using
the mouse. This allows the students and their teachers, represented by avatars, to
move around it. The students and their teacher have different perspectives, just
as in interactional settings of everyday life. The 3D model is supplemented by a
website (see Figure 7.4). As part of the problem the students are asked to identify
which one out of three sequences on the website resource (A, B and C) is similar
to the 3D model of the insulin gene. The correct answer is A.
A
A
A
C
A
T
T
T
T
G
T
A
Figure 7.2 The beginning of the insulin gene. The first two codons “ATG” and “TTT”
are taken down