Never underestimate the power of a pre-board exam!! They are the pointers to your weak areas and makes you habitual of writing an exam. To help you in your this endeavor, your teacher is going to put in a lot of effort. They would be setting board level question papers and shall mark accordingly. Although these marks are not included in the final results but it is advisable to take them seriously.
Pre-boards are a close replica of the actual exam to the extent of even the seating arrangements and use of stationery permissible by the board. The difficulty level of a pre-board could perhaps be a bit higher than boards but once you attempt them you would know your status as regards your preparation. They also help develop answering techniques.
How to Crack your Science Paper
Whether you have a single science paper or three different papers you would still need to split your study plan between the three.
Understanding the various laws, concepts and principles instead of rote learning is any day a better idea.
Use mnemonics to remember the elements of the periodic table. Understand the reasons for various chemical reactions. Remember the characteristics of various chemicals like Acids, bases, alcohols, aldehydes, etc. and their differences.
Make a note of all biological names and revise them thoroughly. Remember all the important terms and test yourself on them. Practice important diagrams and ensure that you label them correctly.