What it is
The International Olympiad of Science (iOS) is SilverZone Foundation’s science olympiad for Classes 1 to 12. Like SilverZone’s maths and English olympiads, it has up to three levels: Level 1 for everyone, written in school, then Level 2 and Level 3 for the top scorers.
SilverZone says the paper is based on the CBSE, ICSE and state board syllabi, and that it includes a section on applied science: using what children learn in class to explain the world around them. The paper has three parts:
- Science: the class syllabus. In Class 1 that means living and non-living things, plants and animals, food, air and water. By Class 8 it covers topics such as crop production, microorganisms, force and pressure, light, sound, and combustion.
- Reasoning and Aptitude: logical and mental ability questions.
- Scholar’s Zone: five harder questions that carry more marks each.
SilverZone publishes a table for each class showing how many questions come from each chapter. For Class 8, for example, the “How Stuff Works” group of physics chapters has the most questions. Checking that table for your child’s class is the quickest way to see where the marks are.
The number of questions and the time depend on the class:
- Classes 1–2: 25 questions in 40 minutes.
- Classes 3–5: 30 questions in 40 minutes.
- Classes 6–8: 35 questions in 40 minutes.
- Classes 9–12: 40 questions in 50 minutes.
Every paper is out of 100 marks. All questions are multiple choice, answered on an OMR sheet, with no negative marking. The paper is in English only.
Who can take it
Students from Class 1 to Class 12, registered through their school. Any school can register with SilverZone as a centre, subject to a minimum number of participating students. If your child’s school does not take part, the school can ask SilverZone for its prospectus.
How it works
The school registers its students and chooses one of the dates SilverZone offers. On that date, the paper is written in school during school hours, with a separate question paper for each class.
From Level 1, students in Classes 3 to 12 can qualify for Level 2 in two ways. One is to rank between 4th and 1003rd in their class in Level 1 with at least 50% marks. The other is to come first in their class in their school with at least 75% marks, where the school has at least 100 participants in the subject. The top three places in each class are then decided at Level 2.
Students who finish first in their class at Level 2, in Classes 6 to 12, go on to Level 3. SilverZone says Level 3 is held in New Delhi, with Dubai as the venue for schools outside India in 2026–27, and that Level 3 winners in these classes are eligible for an educational visit to ISRO.
Results come with olympiad, zonal, state and class ranks, and every participant receives a chapter-wise performance analysis. That report shows marks and ranks, a score for each chapter, percentiles against the zone and all participants, and comparisons with the class. SilverZone describes medals, certificates and other awards at each level on its official site.
When it happens
Level 1 is usually held between October and December. The school picks one of three dates and must register its students in time, usually up to about 30 days before. Level 2 and Level 3 follow for qualifiers later in the year. This year’s dates are on the official SilverZone page; the olympiad calendar shows the usual months for all olympiads.
How to prepare
Follow the chapter table. Because SilverZone tells you how many questions each chapter carries, preparation can be targeted. Make a simple list of the chapters for your child’s class, mark the ones with three or more questions, and start there.
Answer everything. With no negative marking, a blank is a lost chance. Teach your child to mark the likeliest answer and move on, then come back if time allows. (Forty minutes for 35 questions does not leave much spare.)
Explain, don’t recite. Applied science questions often ask what would happen in a situation: a plant kept in the dark, ice left in the sun, a magnet near a nail. Asking your child to explain the reason out loud is excellent practice.
Use the report afterwards. The chapter-wise report is the most useful thing to come out of the paper. It shows which topics need work for school, whether or not the child qualifies.
Plan four to six weeks. Two or three sessions a week, each mixing revision with ten sample questions, is plenty for most classes. For Classes 1–3, keep sessions short and practical: a walk to name plants, or a kitchen experiment. The science prep guide has more by age.
Where daily practice fits
Science is one of the subjects in Ado’s free daily quiz, alongside maths, English, GK and reasoning: 8 questions a day, including a 60-second sprint. That steady habit keeps science ideas and reasoning fresh across the year, not just in the weeks before a paper. Students are ranked only against others the same age, and the Ado Rank builds from their three strongest subjects and never resets.
Good to know
SOF’s International Science Olympiad and Unified Council’s NSTSE are the other widely held school science olympiads. Each has its own pattern and timing, and a child does not need to sit all three; one science olympiad a year, prepared for calmly, is enough for most.