Acikgul, Kubra2024-08-042024-08-0420212148-7456https://doi.org/10.21449/ijate.909316https://search.trdizin.gov.tr/yayin/detay/1131149https://hdl.handle.net/11616/92894The main aim of this study is to develop a useful, valid, and reliable two-tier proportional reasoning skill test for middle school 7th and 8th-grade students. The research was carried out using the sequential explanatory mixed method. The study group of this research comprised of 391 (n(7th-grade)= 223, n(8th-grade)= 168) students. With validity and reliability studies, the content, face, construct, discriminant validity, and reliability coefficient of the test were examined. As a result, the two-tier proportional reasoning skill test with 12 items under 3 factors (qualitative prediction and comparison, missing value, numerical comparison) valid and reliable for adequate values specified in the literature.eninfo:eu-repo/semantics/openAccessProportional reasoningTwo-tier testMiddle schoolArticle8235737510.21449/ijate.9093161131149WOS:000663573300011N/A