The May issue of Instructional Science has recently been published. This issue contains five articles, and at least one of them is directly related to mathematics education. Here is the list of articles in the issue:

• The use of language in understanding subject matter, by Lennart Svensson, Elsie Anderberg, Christer Alvegård and Thorsten Johansson
• Online but off-topic: negotiating common ground in small learning groups, by Trena M. Paulus
• The building of pre-service primary teachers’ knowledge of mathematics teaching: interaction and online video case studies, by Salvador Llinares and Julia Valls
• The learners’ experience of variation: following students’ threads of learning physics in computer simulation sessions, by Åke Ingerman, Cedric Linder and Delia Marshall
• The development of science activities via on-line peer assessment: the role of scientific epistemological views, by Chin-Chung Tsai and Jyh-Chong Liang