The Extended Essay
“The extended essay extended essay of some 4,000 words offers the opportunity for IB students to
investigate a topic of special interest related to one of the student’s six Diploma Programme (DP)  subjects/disciplines. An extended essay can also be undertaken in world studies. The world studies extended essay provides students with the opportunity to carry out an in-depth interdisciplinary study of an issue of contemporary global significance, utilizing two IB diploma disciplines. Both types of extended essay (single-disciplinary and interdisciplinary essays) are intended to promote high-level research and writing skills, intellectual discovery and creativity expected at university. They provide students with an opportunity to engage in personal research in a topic of their own choice, under the guidance of a supervisor (a teacher in the school). This leads to a major piece of formally presented, structured writing, in which ideas and findings are communicated in a reasoned and coherent manner, appropriate to the subject or issue chosen.”

Theory of Knowledge (TOK)
“TOK plays a special role in the Diploma Programme by providing an opportunity for students to reflect on the nature of knowledge, and on how we know what we claim to know.
The fundamental question of TOK is “how do we know that?” Students are encouraged to think about how knowledge is arrived at in different disciplines, what the disciplines have in common and the differences between the disciplinary. TOK therefore both supports and is supported by the study of other DP subjects, as students are required to explore knowledge questions against the backdrop of their experiences in their other DP subjects. Discussion and critical reflection form the backbone of the TOK course. (…) Students gain greater awareness of their personal and ideological assumptions, as well as developing an appreciation of the diversity and richness of cultural perspectives. The TOK course is assessed through an oral presentation and a 1600 word essay.”

Creativity, Activity, Service (CAS)
“CAS enables students to live the IB learner profile in real and practical ways, to grow as unique individuals and to recognise their role in relation to others. CAS is organised around the three strands of Creativity, Action and Service defined as:
• Creativity – arts and other experiences that involve creative thinking
• Activity – physical exertion contributing to a healthy lifestyle, complementing academic work elsewhere in the IB Diploma Programme
• Service – an unpaid and voluntary exchange that has a learning benefit for the student.
Students develop skills and attitudes through a variety of individual and group activities that provide students with opportunities to express their passions, personalities and perspectives. CAS complements a challenging academic programme in a holistic way, providing opportunities for self-determination, collaboration, accomplishment and enjoyment.
Students are also required to undertake a CAS Project that challenges students to show initiative, demonstrate perseverance, and develop skills such as those of collaboration, problem solving, and decision making.”

More details on the official IBO website at: https://www.ibo.org/programmes/diploma-programme/curriculum/