Math By Myself provides time for kinestetic practice of math concepts that are primarily activity based. At the beginning of a new math unit, the activities are mostly review and practice from prior units of study. Then, as the new unit goes on, more of the Math Daily 3 activities become practice and reinforcement related to the current unit of study.
Math by Myself can involve activity boards, various math tools/ manipulatives, or even the use of computers or tablets. --Think of is as "doing" or manipulating materials to solve problems.
Math Writing is time students express and articulate their thinking and understanding by working an a particular math problem or math concept through pictures, numbers, and words, and occasionally by creating problems of their own as well. --Think of it as recording one's thinking in writing.
(These ideas are a condensed version of the Sisters' descriptions on the website. If you go to the home page and click the Math Daily 3 Tab, you can see more information and LOTS of activities to do for each area. https://www.thedailycafe.com/math-daily-3)