True Arch (Roman Arch)

Basically uses a combination of geometry and gravity to form an arch.

The Centering: The wooden frame in the middle is temporary. It acts as a "scaffold" to hold the stones in place while the arch is being built.

Compression over Tension: Unlike a flat beam that might snap under weight, the stones in an arch are cut at angles (called voussoirs). These stones press against each other, redirecting the downward force of gravity outward and down into the ground.

The Keystone: The most critical moment is when the kids place the final, wedge-shaped stone at the very top. This is the Keystone.

Self-Sustaining: Once the keystone is locked in, the wooden support can be removed. The weight of the stones actually makes the structure stronger by squeezing them tighter together.