What is isometry in high school geometry?
Do you have one or two sample questions?
Isometry is a bijective function (transformation) which transforms figure $\displaystyle F_1$ into figure $\displaystyle F_2$ while preserving congruence of line segments.
Formally, for every two pair of points $\displaystyle (A,B)$ and $\displaystyle (A_1,B_1)$
$\displaystyle I(A) = A_1 \wedge I(B) = B_1 \Rightarrow A_1 B_1 = AB$