  Einstein's theory of relativity is largely thought of as one of the most
important discoveries of the 20$^{th}$ century and continues to pass
observational tests over 100 years later. Yet, it is Newtonian gravity, a 350
year old formalism proven to be less accurate than relativity, which is taught
in schools. It has been shown that Einsteinian gravitational concepts can be
well understood by students in both primary and secondary education. In this
paper, a cross-section of students from Yr 7-13 enrolled in an English
secondary school took part in an intervention designed to introduce the idea of
gravity from spacetime curvature. The overall aim of this work is to assess the
viability of including relativity in the secondary curriculum and to ascertain
which year this material would be best placed in. We determine that all year
groups where able to appreciate the effects of curvature to some extent. Visual
demonstrations aided conceptual understanding at Yr 7-8 level, but this does
not have a strong effect on their ideas around the source of the gravitational
force. Participants in Yr 9-13 were able to understand concepts beyond those
introduced in the demonstrations. However, a deeper understanding of curvature
as the source of the gravitational force is not seen until years 12 & 13. We
find that those in Yr 13 have the best overall understanding of the concepts
introduced during our intervention.
