I absolutely love using math journals in kindergarten! I think it is such an essential skill for students to be able to record their thinking. I have the students do math journals as part of their rotations for math workshop. It is a great way to differentiate instruction. I can give each math group different math prompts that are at their level. Before doing journal prompts, there are a series of activities that I have students to complete so they have things to reference when they are working in their journals. Some things that I include are a 100s chart, numbers, ten frames, number words, tally marks, coins and their values, shapes, etc. I also include vocabulary. I just created a packet of math vocabulary that kindergartners need to understand. It is aligned with the Common Core Standards. The packet contains the words: sort, pattern, triangle, rectangle, square, circle, addition and subtraction. Each word has a graphic organizer with a definition, illustration, example and non-example. Check it out here!