Been a moderator here for a number of years (since mid 2007 when
I was in Germany), and have helped countless students with
their questions in maths, physics as well as education related
questions.
The name "ExamWorld" also started off here, with
examworld.blogspot.sg as the initial blog which help students, and
now, ExamWorld as an independent publisher of books for
students.
SgForums Homework Forum holds dear to me. Because of that, I'm
offering a discount to buyers of my books on this forum. 15%
discount for the first 15 buyers of each title. More details
below...
Introducing the books:

Books For GCE 'O' LEVEL
Explain That! GCE ‘O’ Level Physics, 2nd Ed. (ISBN
978-981-47-6192-5)
Explain That! GCE ‘O’ Level Chemistry (ISBN
978-981-47-6193-2)
Explain That! GCE ‘O’ Level Science (Physics/Chemistry) (ISBN
978-981-47-6194-9)
What the books are about
Explain That! is a series of comprehensive guides designed to
help students master the skill of answering qualitative questions.
Each title comprises a well-curated selection of questions which
covers a variety of key ideas and concepts. These books train
students to construct their explanations using examiner-style
phrasing, giving them greater confidence before and during the
examinations.