Practice:
https://www.thatquiz.org/tq/practicetest?8xa30ey8g9m
http://www.softschools.com/math/geometry/triangles/congruent_triangles/
https://www.ixl.com/math/geometry/proving-triangles-congruent-by-sss-sas-asa-and-aas
https://www.proprofs.com/quiz-school/story.php?title=corresponding-parts-of-congruent-triangles
https://www.ixl.com/math/geometry/congruence-statements-and-corresponding-parts
https://mathbitsnotebook.com/Geometry/CongruentTriangles/CTrecognize.html
Instruction:
https://www.texasgateway.org/resource/applying-triangle-congruence-relationships
http://www.wikihow.com/Write-a-Congruent-Triangles-Geometry-Proof (How to write two-column proof)