Public elementary and secondary education; Office of Mathematics Improvement established; mathematics improvement and advancement policies and programs. Establishes several new programs and policies for the purpose of improving mathematics instruction and student learning outcomes in public elementary and secondary schools in the Commonwealth, including (i) directing the Department of Education (the Department) to establish the Office of Mathematics Improvement (the Office) as an office within the Department; (ii) directing the Director of the Office, in collaboration with the Department, to establish an Elementary School Mathematics Advisory Task Force, a Middle School Mathematics Advisory Task Force, and a High School Mathematics Advisory Task Force; (iii) creating several grant programs aimed at incentivizing, encouraging, and expanding opportunities for improving mathematics instruction for educators and mathematics learning outcomes for students, including the Summer Mathematics Intervention Grant Program, the Advance Placement Mathematics Exam Fee Elimination Fund and Program, the Mathematics Improvement and School Support Grant Program, and the Advanced Mathematics Teacher Incentive and Support Grant Program; (iv) making several changes to staffing requirements relating to teachers providing mathematics instruction, including creating a mathematics specialist microcredential program and establishing staffing ratios for mathematics specialists in public schools and permitting schools to use state funding appropriated to support meeting such staffing ratios to support teachers in completing the professional development or training necessary to receive the requisite licensure or endorsements; and (v) requiring the Department to expand the advanced mathematics courses offered through Virtual Virginia, as established pursuant to applicable law, for the purpose of ensuring that students attending public schools across the Commonwealth have access to a full range of advanced mathematics courses. The bill also (a) directs the Board of Education (the Board) to modify its regulations to increase the flexibility of receiving an Algebra I add-on endorsement for teachers; (b) directs the Board, in collaboration with the Office, to develop and approve a Geometry add-on endorsement for teachers; (c) requires the development and dissemination of various guidance documents for school boards and school counselors and online training programs and modules for educators relating to expanding and encouraging mathematics instruction and education, particularly advanced mathematics instruction and education; and (d) requires the Department to compile and post in a publicly accessible location on its website by August 1 of each year a report detailing the impact of the provisions of the bill on expanding mathematics offerings and improving mathematics learning outcomes in public schools across the Commonwealth. The bill provides timelines for modifying regulations to implement the provisions of the bill.