Based on the theoretical understandings from Legitimation Code Theory (Maton, 2013) and
Systemic Functional Linguistics (Martin, 2013) underpinning the research discussed in this
special issue, this paper focuses on classroom pedagogy to illustrate an important strategy
for making semantic waves in History teaching, namely temporal shifting. We begin with
a brief contextualisation of how Legitimation Code Theory (LCT) and Systemic Functional
Linguistics have been used together to investigate cumulative knowledge-building before
outlining how the LCT concepts of semantic gravity and semantic density were enacted in
linguistic terms for this research in order to understand the linguistic resources marshalled
by actors in making semantic waves. The paper then moves on to consider temporality
from both linguistic and sociological perspectives and to demonstrate how it is implicated
in movements up and down the semantic scale to create semantic waves