Ratios and proportions are foundational to student understanding across multiple topics in mathematics and science. In mathematics, they are central to developing concepts and skills related to slope, constant rate of change, and similar figures, which are all fundamental to algebraic concepts and skills.

Dougherty, B., Pedrotty Bryant,  D., Bryant, B., Shin, M. 2016,  Teaching Exceptional Children Vol 94(2):96-105, DOI: 10.1177/0040059916674897