In these maps, I identify the bubbles of research published within the JRME between 1970 and 2019. For each decade, I identify and name the bubbles that constitute the research foci of the field as published within this journal. This spherological analysis (Sloterdijk, 2011, 2016) considers the bubbles and foams formed by the 1,090 published in the JRME between 1970 and 2019. These articles together include 33,273 citations. This analysis shows what counts as mathematics education research is fluid. The shift in which topics comprise the foams of each decade and the the shifting position of the bubbles across time reveals the field's volatility.