One of the most important math concepts for students in third through fifth grade is fractions. Understanding the underlying concepts and how to manipulate fractions (with all four operations: add, subtract, multiply, and divide) as well as convert to decimals or reduce the simplest form will allow a student to thrive in middle school math.
For those of you in the MMSD, the Bridges Math Curriculum website has both a parent section and a free game section (that aligns with the curriculum). https://www.mathlearningcenter.org/families/bridges2 Scroll down until you see:
A video that shows a lesson I did with my third-graders as a fraction extension.