Which operation would students in Mr. Jansen's class likely use next after mastering addition?

In Mr. Jansen's class, after students have mastered addition, the logical next step is likely two-digit subtraction. This choice builds upon their understanding of addition by introducing a new operation that often relates to it—subtraction. Students generally learn addition and subtraction as complementary operations, and mastering addition equips them with foundational skills that they can apply when learning to subtract.

Moving to two-digit subtraction after mastering addition allows students to utilize their knowledge of place value and the regrouping process that is often part of both addition and subtraction. With a solid grasp of addition, students can better understand and compute two-digit subtraction problems by thinking about how subtraction is the inverse of addition.

In contrast, focusing on single-digit addition would not push the students' skills further since they have already mastered that area. Two-digit addition, while a natural progression, does not introduce a new concept or operation. Finally, jumping directly to multiplication could be overwhelming, as it requires a different set of skills and understanding than what has been cultivated through addition and subtraction. Thus, two-digit subtraction is the most logical next step in their mathematical journey.