Ben loved to take things apart. When his family's old radio stopped working, he opened it to see what was inside. So when his teacher announced a science fair, Ben knew exactly what to do: he wanted to build a robot.
For a month, Ben worked every afternoon in his grandfather's garage. He used wheels from an old toy car, a small motor and a plastic box for the body. His grandfather, Joe, helped him with the wires. The robot could move forward and turn left when it saw a wall.
On the day of the fair, Ben put the robot on the table and pressed the button. Nothing happened. Ben's face turned red. Then he remembered: the battery! He had used it all the night before. Luckily, a girl at the next table had an extra one.
The robot moved, turned and stopped in front of the judges. Ben didn't win first prize, but he won something better — a new friend, Sarah, the girl with the battery.