The ICSE curriculum is also supposed to be very difficult. There are several subjects in the 9th and 10th grades such as math, biology, physics, chemistry, geography, history, English language, English literature, economics/computers etc, and a second language. The addition of Math and sciences would be helpful for everyone.

Here is the ICSE syllabus for math:

1, banking

2. value added tax

3. shares and dividend

4. Linear inequations in one variable

5.Quadratic equations

6.word problems on quadratic equations

7. ratio and proportion

8. remainder and factor theorums

9.matrices

10.arithmetic progression

11.geometric progression

12.reflection in quadrants of graphs

13.section and mid point formula

14. equation of a line

15. similarity

16. loci

17.circles

18. tangents and intersecting chords

19. construction of circles

20. surface area and volume of cylinder, cone and sphere

21. trigonometrical identities

22.heights and distance

23. histograms, frequency polygon and ogives

24.mean, median, quartiles and mode

25.probability

Here are the biology ICSE chapters;

1. cell

2.structure of chromosomes, cell cycle and cell division

3. genetics

4. absorption by plant roots

5. transpiration

6. photosynthesis

7. the circulatory system

8. the excretory system

9. the nervous system

10. the endocrine system

11. the reproductive system

12.population

13. immunity, immunisation, antitoxins,antiseptics, disinfectants and antibiotics

14.the red cross and WHO

15. pollution 

These are the physics chapters

1. force

2. work, energy and power

3. machines

4. refraction of light at plane surfaces

5. refraction through a lens

6. spectrum

7.sound

8. current electricity

9. household circuits

10. electro magnetism

11. heat (caliorimetry)

12. radioactivity

Chemistry chapters for the ICSE;

1.trends in properties in the periodic table

2. chemical bonding

3.acids, bases and salts

4.uses of ammonium hydroxide and sodium hydroxide

5.mole concept and stachiometry

6. electrolysis

7.metallurgy

8.study of hydrogen chloride

9.study of ammonia

10.study of nitric acid

11,sulphuric acid

12. organic chemistry 

        -organic componds

        -alkanes

         -alkenes

         -alkynes

        -alcohols

          -carboxylic acids

This actually may not happen.Khan academy is not focused on teaching a specific curriculum. It teaches us the concepts that are common all around the world. You can always try searching for the topic individually and learn the concept. Since ICSE is based on conceptual understanding, learning those concepts will help you!!  :D

There are more than 10 languages in ICSE curriculum.Do you want all of those languages ?