Lessons in Chemistry

Calvin receives yet another letter from the woman claiming to be his mother. He thinks about how his supposed father, in turn, has never written to him. The only person in the world to whom Calvin had confided about his biological father was a pen pal named Wakely; when Calvin expressed that he wished his father were dead, however, Wakley had completely stopped writing back. Fearing this reaction from Elizabeth, Calvin has never confided in her about his father.

Because Six-Thirty is an extremely intelligent dog, Elizabeth had never used a leash on him until the city passed a leash law. Elizabeth convinces Calvin to use the leash when he takes Six-Thirty out running with him in the mornings. One dark and drizzly day, Elizabeth is unable to sleep and goes in to work before dawn. Calvin decides to run to work and meet her there, taking Six-Thirty on the leash along with him. Calvin dies that day, 37 minutes after he leaves the house.

On their way to work, Calvin and Six-Thirty jog past the police station. Because of budget cuts, the policemen have not been able to inspect and tune up their cars; a number of these cars backfire as Calvin and Six-Thirty pass them, and the noise terrifies Six-Thirty who is reminded of his bomb-sniffing training.