Bachillerato

The equivalent to "Bachillerato" could be one of the following options: "A-levels" or "Sixth form". British students over 16 typically study in the sixth form of a school, in a separate sixth form college, or in a Further Education College. Students typically study level 3 qualifications such as A-levels, BTEC National awards and level 3 NVQs (National Vocational Qualifications). In Britain, students at this level would be in years 12 and 13, which is key stage 5. 
   
If we want to make a distinction based on the subjects chosen, we could talk about "branches".
Click on the link below to hear how to pronounce these words. 

Asignaturas troncales y optativas

You may say:
Asignaturas troncales: Core subjects
The national curriculum for England is organised on the basis of 4 key stages and 12 subjects, classified in legal terms as ‘core’ and ‘other foundation’ subjects.
Asignaturas optativas: Optional subjects

Evaluación

Assessment:

Evaluación inicial: Initial assessment
Evaluación formativa: Formative assessment/ Assessment for learning
Evaluación sumativa: Summative assessment
Estándares de aprendizaje evaluables: Learning standards

Click below to hear the correct pronunciation. 

Actividades

Different types of activities you may use with your students/ your students may take part in:

Actividades de refuerzo: Reinforcement activities
Actividades de ampliación: Extension activities
Actividades complementarias: Complementary activities
Actividades extra-escolares: Extracurricular activities 

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"Casilleros"

In an office, you can say 'pigeon hole' or 'cubby hole', but in class you can also tell pupils 'Put your things in your tray' (they usually have a tray in the pigeon holes) or just tell them 'Put your  worksheets away tidily, please'. If they have plastic folders then you can also say 'Put the worksheet in the folder.'
Click on the link below to hear how to pronounce these words.

"Director" "Jefe de estudios"

You can say:

Headteacher, headmaster or headmistress, head, chancellor, principal or school director to refer to the teachers with the greatest responsibility for the management of a college. 
Deputy head teacher to refer to the second most senior teacher in a school. 
Director of studies to refer to a member of staff who has responsibility for overseeing the curriculum. 
For a full list of roles in UK schools see: http://www.skillsforschools.org.uk/roles-in-schools



Click below to hear the correct pronunciation.