Are All the Triangles Similar?

This GeoGebra lesson explores how to determine whether different triangles are similar, using interactive visual evidence and measurable properties. It emphasizes the key ideas of triangle similarity—corresponding angles and proportional side lengths—along with arithmetic checking of ratios after applying geometric transformations (e.g., translation to align configurations). The construction concept is to create multiple (including scalene) triangles, measure/compare their angles, and then use geometric transformation tools to map one triangle’s position to another while preserving shape. Finally, compute and compare the ratios of corresponding sides via arithmetic operations to confirm or refute similarity. Suitable for middle school and high school geometry lessons, especially for teaching and reviewing similarity criteria through dynamic geometry verification.