This article is concerned with understanding situations
in which speakers talk in the presence of scientific inscriptions
(lectures in science classes, public presentations). Drawing
on extensive video materials accumulated in middle and high
school science classrooms and university lectures, we develop
a framework for the resources speakers make available to their
audience for understanding what the talk is about. We distinguish
three situations according to the nature of reference to the
phenomenon talked about: (i) talk is about phenomenon but mediated
by reference to a two-dimensional (2-D) inscription; (ii) talk
is about phenomenon but mediated by reference to a
three-dimensional (3-D) inscription; and (iii) talk is directly
about phenomenon. Associated with these three situations are
different body orientations, distances from inscriptions, and
types of gestures. When speakers laminate talk characteristic
of two different types of situations, the orientation
“up” can become “down” and
“down” can become “up,” potentially
leading to confusing statements.