“Hi,” Lucas said, picking up a wooden crossbeam.

Ethan pulled an uncomfortable metal folding chair up to the table and quietly sat down.

He leaned forward, resting his elbows on his knees as he studied the balsa wood joints.

“Where does the main force go when a heavy truck hits the middle?” Ethan asked.

Lucas pointed his pencil at a glued diagonal strut.

“The tension travels down through these four outer members into the anchor plates,” Lucas said.

“If the middle beam gives half a millimeter, the whole load shifts to the deck piers.”