you can not study all the subjects of ca foundation from class 11 because most of the syllabus of ca foundation is from class 12

But u can study some subjects or topics of ca foundation. They are

1.Business economics

2.Acountancy

3.Statistics and logical reasoning

4.Business correspondence and reporting

5.Business law

1.Business economics

This subject can be started along with your class 11 and 12 economics because most of the syllabus of business economics is similar with class 11&12 , but a little advance level

If you able to carry this subject preparation along with your class 11 and 12 you can get good marks in foundation as well as you can also score good in your 11 and 12th boards

2.Financial accounting

Accounting is the base of chartered accountancy course and most of the accounting of ca foundation is from class 11 & 12 but the accountancy of ca foundation is complicated than 11 & 12

So if you are able to carry accounts of ca with your boards syllabus you will cover the whole 100 marks of ca foundation and you will 100% nail your class 11 and 12 also

3.Statistics and logical reasoning

Iam suggesting you this subject because its the most easy scoring subject which can give you 60 marks in paper 2

So don’t miss the chance. Even one mark also cost you 6 moths

Note: If you are a commerce student with non maths you should also have a look at Business mathematics

4.Business corresponding and reporting

As long name its not that much complicated simply it is english which will give you 40 marks

So focus on english grammar form starting

5.Business law

you can also study business law along with your class 11 and 12 but I will not suggest you because le clasues of business keeps changing and as it is a theoritical subject you may forgot with out revision

and this will be a burdain as there is no role of business law in class 11 and 12

:)By studying these topics you can cover more than half syllabus of ca foundation till your class 12 ( up to 240 marks )

You can study by using icai modules and youtube. specially I recommend you swapnil patni for business economics , grooming education academy for financial accounting and CTC commerce classes for remaning subjects

All the best student,

Hope this helps you.