Some ways to strengthen the basics are:Write down what you understood and create revision notes for your aid, especially in Biology.Divide bigger and complex topics into smaller parts for easier understanding.Take your time with a concept instead of rushing into finishing it. Be clear with the fundamental concepts in chemistry. Try as much as you can to understand a concept through visual learning, as you can explain that concept in your own words if you know how it works. Grasping the basic concepts through practical examples is very useful.