Start with high-confidence algebra for kids books, then narrow by subgenre or adjacent topics.
Mcgraw-hill Education Algebra I Review and Workbook
Sandra Luna McCune
Math Pact, Elementary
Karen S. Karp, Barbara J. Dougherty
The Ultimate Grade 3 Math Workbook
IXL Learning
The Ultimate Grade 4 Math Workbook (IXL Workbooks)
