"Pa didn't go away very often, but when he did, it took all of us working together to get him ready. He was only going to be gone 3 weeks to Mankato and other places on errands for Mr. Hanson, with Mr. Edwards to help him and keep him company. But Pa said, when it came to leaving home, it took a lot of people to get him started."
After Pa and Mr. Edwards leave, the girls head for school but Laura's dawdling makes them late. Miss Beadle is telling the class about the annual Scholarship Award with the award being a new Webster's dictionary. At home, Ma tells Mary not to expect too much on the exam. The next day, Mary asks Miss Beadle for help in locating a history reference book so Miss Beadle loans her hers. Mary reads the book all the way home and every chance she gets even after the girls have gone to bed. Laura tells her to turn out the light and get to bed. Mary sneaks downstairs and goes out to the barn to study the book by lantern light.
Later, Mary falls asleep with the lantern sitting on a stool between her legs. During her sleep she turns over and knocks the lamp onto the hay igniting it. The horse gets excited and wakes up Mary. She tries to put out the fire but only succeeds in spreading it. She runs to the house yelling for Ma. Ma comes out, runs to the barn, gets the animals out and manages to extinguish the fire out before it gets too bad. Ma lights into Mary about setting the fire and forbids her from taking the examination. She tells her to go to school and tell Miss Beadle that she's not taking it. As they return to the house, Laura consoles a distraught Mary.
The next morning, Ma talks to Mary. She tells her that she was frightened last night and that that is why she was so harsh. Ma's about to say something else but a distraught Mary asks to be excused. She wants to go clean up the burned area in the barn. Cleaning up the barn, Mary discovers the history book Miss Beadle loaned her. It is badly burned. After Sunday services, Caroline seeks counsel from Rev. Alden. He tells her that he has seen Charles and Mr. Edwards at their campsite. Rev. Alden advises Caroline to keep Mary's punishment (not being able to take the examination) in place. At the Mercantile, Mary notices a Help Wanted sign and asks Mr. Oleson about the job. He tells her she can have the job if her Ma approves and she can start the next day after school. Mary finds out that she'll be making 50 cents a week and that a new history book costs one dollar.
At school, Mary passes up an opportunity to tell Miss Beadle about her not taking the exam. Laura asks Mary why she didn't tell Miss Beadle but Mary wants to wait until she has enough money to buy a replacement history book. At home, Mary asks for permission to take the job at Oleson's. The next day, Mary is working at the Mercantile when Nellie comes in making some snide comments. Miss Beadle stops by for some sugar and Mary overhears Nellie telling her that the store carries all of the reference books that will be used for the examination. When Miss Beadle asks Mary when she finds time to study for the exam, Mary ignores the question until Miss Beadle repeats it--then Mary just lies to her.
It is almost dusk when Mr. Oleson gives Mary a ride home. Seems he accidentally locked up the store with her still in it, studying the reference books. After Laura goes to bed, Mary continues to study for the exam under the moonlight. Mary thinks that if she takes the test and wins, Ma will be OK with it. After school, Mary returns to work at the Mercantile, spending every free moment studying the reference books there. In school, Mary is starting to show signs of fatigue. After three weeks of work, Mary receives $1.50 from Mr. Oleson. She turns around and uses $1.00 to buy a new history book. At school, Miss Beadle reminds everyone that the exam will be held tomorrow. Mary gives Miss Beadle the new history book. At home, Mary tells Ma that she got $.50 for working three weeks at the Mercantile. After dark, Mary continues to study. When Caroline drops some eggs off at the Mercantile the next day, Mr. Oleson remarks that he is sure going to miss Mary as she was a hard worker. Caroline makes a comment about Mary getting only $.50 for the three weeks but he tells her it was $.50 a week and that he was surprised that Mary bought a new history book with her earnings, especially since she had read every reference book in the store.
At school, Miss Beadle is about to start the exam and Laura looks anxiously at Mary. Since Laura is not taking the test, she goes outside for recess. Ma sees her sitting on the school steps and asks her where Mary is. Laura tells her she is inside. Ma steps inside and watches Mary at her desk obviously taking the test. She leaves the school without saying a word. The exam is over and the winner is announced. Mary runs out and Laura is about to follow her when Miss Beadle asks her to stay after. Miss Beadle gives Laura a ride home. She hands Caroline Mary's examination which she didn't take. Instead she wrote Miss Beadle a note stating that she wasn't taking the exam and her reasons why. Ma goes looking for Mary and finds her sitting under a large tree. They run into each other's arms and apologize to each other before heading home.