Students were retaught english-german vocabulary after lags of 0,1, or 10 days and tested 35 days later.
When vocabulary was tested, students from lags of 1 or 10 days performed better than those from 0 lag.
We reatin information better when there are longer breaks in between presentations of the same information.
See the full study here :
Küpper-Tetzel, C.E., Erdfelder, E. & Dickhäuser, O. (2013) The lag effect in secondary school classrooms: Enhancing students’ memory for vocabulary. Instr Sci 42, 373–388 . https://doi.org/10.1007/s11251-013-9285-2