<p>This study investigates the teaching of early years mathematics within an intervention using play-responsive teaching (PRT). It focuses on ways sequences characterized as play-responsive mathematics teaching (PRMT) and mathematics teaching (MT) address the nature of the mathematics that is made available to learn. A previous study revealed that when teachers and children engaged in play-responsive teaching (PRT) with an emphasis on mathematics, particularly cardinality, three distinct sequences were identified: play without mathematics, mathematics teaching without play (MT), and play-responsive mathematics teaching (PRMT). In this article, the two latter sequences are analyzed with a focus on teaching quality. In this context, the quality of teachers’ mediation refers to how preschool teachers make mathematical content accessible to children and how they support children’s meaningful participation in the learning sequences. The results indicate both advantages and disadvantages of play-responsive teaching. Specifically, MT sequences were rich in terms of the mathematics that was made available to learn, caused by a structured use of artifacts. In the PRMT sequence, however, children’s agency and responsiveness in mathematics were more prominent than the mathematics that was made available to learn. Thus, the content and scope of the two sequences complement each other by offering diverse learning opportunities. While mathematical content occasionally recedes in PRMT, the children remain engaged in the activities. Furthermore, integrating play with mathematics makes mathematics important and meaningful for the participating children.</p>