What does this sentence suggest?

For her first month in the city, Lina rode the Number 9 bus with her eyes on the floor. Her cousin had written the stops on an index card, and she kept it in her coat pocket and counted them under her breath: the hospital, the car wash, the park with the broken fountain, then school. Seven stops. She never looked up long enough to learn what anything else was called.

Then her mother started a job on the far side of town, and Lina's little brother, Sami, became her responsibility in the mornings. He was eight, and he asked questions the way other people breathed.

“Why is that man wearing two hats?” “Why does the bus kneel down?” “Why are we going past the school?”

Lina's head snapped up. The school was sliding by on the right, and the bus was not slowing. Someone had pulled the cord at the stop before hers, and somewhere between the hats and the kneeling she had lost her count.

She pulled the cord herself, too late, and the bus let them off two blocks past the gate, in front of a laundromat she had never seen. Sami looked up at her with his whole face, waiting to find out whether this was a disaster.

She made herself look around. Above the rooftops stood the water tower with the city's name painted on it, the one she could see from her classroom window during math. If she could see the tower from the school, then the school could be found from the tower.

“We walk toward that,” she said, as if she had planned it.

They were four minutes late. The office secretary wrote them both passes without asking why. That afternoon, on the ride home, Lina kept her eyes on the window and named every stop out loud before the driver did, and Sami, who had never once been quiet on that bus, listened.