To show that two triangles are the same size and shape, we can use some specific rules about their parts. Here are those rules:

1. SSS (Side-Side-Side): If all three sides of one triangle match the three sides of another triangle, then the triangles are congruent.

2. SAS (Side-Angle-Side): If two sides and the angle between them in one triangle are the same as two sides and the angle between them in another triangle, then the triangles are congruent.

3. ASA (Angle-Side-Angle): If two angles and the side between them in one triangle match two angles and the side between them in another triangle, then the triangles are congruent.

4. AAS (Angle-Angle-Side): If two angles and a side that's not between them in one triangle are the same as two angles and a matching side in another triangle, then the triangles are congruent.

5. HL (Hypotenuse-Leg for Right Triangles): If the longest side (hypotenuse) and one leg of a right triangle are the same as the hypotenuse and one leg of another right triangle, then those triangles are congruent.

By using these rules, we can easily check if two triangles are congruent!