Spaced Repetition for IGCSE Chemistry Revision

The biggest enemy of IGCSE Chemistry revision is forgetting. You study the ion tests on Monday, feel confident on Tuesday, and by the following Monday half the colours have drifted out of memory. This is not a personal failing. It is how human memory works: new information decays rapidly unless it is retrieved at the right moments. Spaced repetition is the system that times those moments for you.

The forgetting curve and why spacing works

Hermann Ebbinghaus demonstrated in the 1880s that memory decays exponentially after learning. Without review, you forget roughly half of new material within a day and most of it within a week. But each successful retrieval slows the decay. Review at the point where you are about to forget, and the memory resets at a stronger level with a longer half-life. Repeat this cycle and the interval between reviews stretches from days to weeks to months.

This is why cramming the night before works for the exam tomorrow but fails for the exam next month. Spaced repetition builds the kind of durable memory that survives across multiple papers and the gap between Paper 2 and Paper 4 in the same session.

What to space in IGCSE Chemistry

Not everything in 0620 benefits equally from spaced repetition. The technique is most powerful for:

Pure memory content:

• Qualitative analysis: cation tests, anion tests, gas tests, flame colours
• The reactivity series (K, Na, Ca, Mg, Al, C, Zn, Fe, H, Cu, Ag, Au)
• Colours of common compounds and precipitates
• Definitions: exothermic, endothermic, catalyst, electrolyte, isotope, homologous series
• Organic functional groups and their reactions

Equations:

• Balanced symbol equations for key reactions across every topic
• Ionic half-equations for electrolysis
• Word equations for organic reactions (combustion, addition, substitution)

Conceptual pairs:

• Strong acid vs weak acid
• Ionic bond vs covalent bond vs metallic bond
• Oxidation vs reduction (in terms of oxygen, hydrogen, and electrons)

Content that requires problem-solving, such as stoichiometry calculations, is better practised through timed questions than flashcards. You cannot meaningfully “card” a mole calculation. But you can card the formula relationships (moles = mass / Mr, concentration = moles / volume) so the tools are instantly available when you sit down to solve.

How to build effective chemistry flashcards

A flashcard tests one fact in one direction. Follow these rules:

One fact per card. “List all Group VII properties” is a bad card. “What is the colour of chlorine gas?” is a good card. If you need ten facts, make ten cards.

Card in both directions. For ion tests, make one card asking “How do you test for iron(III) ions?” and another asking “What ion gives a red-brown precipitate with NaOH(aq)?” The exam asks in both directions, so your cards should too.

Include the equation where relevant. If the card is about the reaction of magnesium with hydrochloric acid, the answer should include Mg + 2HCl → MgCl2 + H2, not just “magnesium chloride and hydrogen.”

Use precise language. “It turns red” is not the same as “the solution turns from green to yellow to orange.” Examiners award marks for specific observations, and your cards should train that precision.

A practical spacing schedule

If you use Anki, the algorithm handles intervals automatically. For paper cards or a manual system, use this schedule:

Review number	Interval	Example
1	Same day (evening)	Learn cards Monday morning, review Monday evening
2	+1 day	Tuesday
3	+3 days	Friday
4	+7 days	Following Friday
5	+14 days	Two weeks later
6	+30 days	Monthly thereafter

If you get a card wrong at any stage, reset it to review 1. This is strict but effective: a card you get wrong has not been learned, regardless of how many times you got it right before.

Fitting spaced repetition into your school week

Malaysian students sitting 0620 typically balance chemistry with seven or eight other subjects, plus co-curricular activities and sometimes tuition classes in the evening. Spaced repetition works precisely because it is short:

• Morning (10 minutes before school): Review due cards. A mature deck of 200 cards surfaces about 15-25 cards per day. This takes under ten minutes.
• Evening (5 minutes): Review any new cards added today. New cards are the hardest because they are fresh, so keep daily additions small: 5-10 new cards maximum.
• Weekend (15 minutes): Longer session to catch up on any skipped days and add new cards for topics covered that week.

The total weekly commitment is about 90 minutes, spread across every day. Compare that with a three-hour cramming session that produces worse retention.

Building the deck across the year

Do not try to card the entire syllabus in one sitting. Build the deck as you study each topic:

• After covering acids, bases and salts in class, add cards for the key definitions, reactions, and salt preparation methods that week.
• After a past paper, card any fact you got wrong or could not recall.
• After reviewing a topic guide like metals, add cards for the extraction methods and reactivity comparisons.

By the time formal revision begins, your deck already exists and most cards are at long intervals. Revision becomes a matter of tightening up weak cards rather than building from scratch.

When spaced repetition is not enough

Spaced repetition holds facts in memory. It does not teach you to apply them. If you can recall that “the rate of reaction increases with temperature” but cannot explain why in terms of particle collisions and activation energy, the flashcard has done its job and you now need a different kind of practice. Use active recall exercises and past paper questions to build application skills on top of the factual base that spaced repetition provides.

The two methods are complementary. Spaced repetition ensures you never walk into the exam missing a basic fact. Active recall and past papers ensure you can deploy those facts under exam conditions. Together, they are the most efficient revision system available for a content-heavy subject like 0620.