In 1837, Horace Mann worked for all the following public school reforms in Massachusetts except;
A.raising teachers’ salaries.
B.pressuring the legislature to increase the funding for schools.
C.opening the nation’s first public high schools.
D.starting teacher training schools.
C.updating the curriculum.

Hint: Horace Mann, an educationist, and a politician advocated for reforms in common schools pattern, structure, teachers’ training, and other necessary reforms for accessing the quality of education for all in a democratic society. He was likewise against bondage.

Complete answer:
In 1837, Horace Mann worked for all the public school reforms in Massachusetts except opening the nation’s first public high schools. As they were already there.

Hence, the correct answer is option (C).

Additional information:
As Mann’s childhood was not that pleasant and was filled with poverty and hardships, he realized the importance of quality of education and teachers’ skills. Although he managed to get admission to Brown University, he started to work for educational and social reforms. As the schools' control was in the hand of economy-minded people, the quality of education deteriorated. As a result, a reform movement was started that led to the establishment of a state board of education. In 1838, he started a biweekly named Common School Journal and served as a lecturer to the interested group of citizens. He focused on universal popular education paid for, controlled, and sustained by the interested public. It must be free of sectarian religious influence and only well-trained professional teachers must provide it. He advocated that education should be provided in schools to children from all backgrounds.

Note: His efforts put some elite section in anger as their stakes were being affected. But Mann’s efforts were put forth by every stakeholder. Hence, even today, he is known for his efforts to transform the public education system in the US.