The Secondary School Curriculum at Tree Top International School is based IGCSE and the teachings of Maria Montessori. The overarching mandate for the curriculum is to develop the whole student while imparting the academic tools necessary for success in high school, university, and the working environment. Students are evaluated in a number of ways, including but not limited to, traditional grades, portfolios, and ratio scores. 

The Secondary School at Tree Top International is designed for 100% involvement by students. The academic aspects are pre-university quality, but the community building component is equally important.

The English Curriculum includes intensive reading with a strong focus on developing critical thinking skills. Students read one challenging novel, play, or featured articles per term. By looking at the many elements that go into a piece of literature, students gain the skills necessary to explore the work to find the larger meaning and think critically about what they have read. Students will also increase their writing skills, focusing largely on organisation of an academic essay.

Students are also encouraged to develop their skills by evaluating their own work through the development of portfolios in which they collect evidence of their work in Science. The goal is to produce students who are not only aware of the facts of science, but who also understand the process and context that produces those facts, and who can examine the impact of science on their lives in an informed and intelligent way.