The demand for improving student interest in science has increased efforts toward teaching Einstein's theory of general relativity in schools. Research has already shown that teaching Einsteinian gravity at the secondary level is feasible, however, appropriate resources must be readily available for science teachers to make Einsteinian gravity part of the school curriculum. This paper addresses student learning through activities that include simple hand-held experiments that help secondary school teachers and their Year 7 students grasp two key concepts that led Einstein to develop his theory of gravity -- the speed of gravity and his 'happiest thought' about free-fall and weightlessness. The first experiment allows students to conceptualise the speed of gravity. Three further experiments help them explore free-fall and weightlessness in different situations. We analyse the evolving conceptions of Year 7 students (N = 44) on understanding free-fall in an 8-lesson program that includes these experiments in the third lesson. Improvements in students' understanding over 8 lessons, showed that time and reinforcement were needed to assimilate the concepts. After eight lessons, 86% of students gave an Einsteinian explanation of free-fall.