Paper 1A guide

How to score higher in Paper 1A

This guide comes from a study of the 8 HL Paper 1A papers of the new syllabus so far (May 2025, November 2025 and May 2026: 320 questions). There is no trick for guessing: the right letters are spread almost exactly evenly. High scores come from knowing every topic and using the same method for every question. The general numbers are on the Paper 1 guide.

1. The paper has a fixed shape

• 40 questions, 1 mark each, in theme order: A, then B, C, D, and E at the end.
• Question 1 has always been kinematics (A.1). Question 40 has always been stars (E.5), often a parallax question.
• About 9 questions from Theme A, 7 from B, 7 from C, 8 from D and 9 from E.
• Use this as a check: if question 12 looks like a gravity question, you have probably lost your place on the answer sheet.

2. Every topic comes up

22 of the 24 sub-topics appeared in at least 6 of the 8 papers. Skipping a topic is a real risk. These come up most (about 2 questions in every paper):

The counts come from only 8 papers: use them to decide what to practise most, not to guess what will come.

3. Four kinds of question, four routines

Theme A has the most calculations (the longest working). Themes D and E have the most statement questions. Themes C and D have the most graphs.

4. The 4-step method for every question

1. Cover the options. Read the question and predict the answer. The wrong options are written to catch common mistakes.
2. Underline the numbers, the units and words like not, constant, maximum. Many lost marks are reading mistakes.
3. Write one line of physics: a formula or a small sketch. It fixes signs and directions.
4. Check the units, the size, the direction and an extreme case (r → ∞, v → c). It takes 10 seconds and often removes two options.

5. Time

• Use 2 minutes per mark. In the exam, 1A and 1B share 2 hours at HL: 80 minutes for 1A (40 marks) and 40 minutes for 1B (20 marks). At SL: 50 minutes for 1A (25 marks) and 40 minutes for 1B.
• Pass 1: go in order. If you cannot see the first step in 20 seconds, circle the question number, choose your best answer and move on.
• Pass 2: go back to the circled questions. Start with those where you can cross out two options.
• Last 3 minutes: check the answer sheet. Every question has exactly one answer, on the right line. A wrong answer loses nothing, so never leave a blank.
• The practice papers on this site use the same time: 80 minutes for HL 1A and 50 minutes for SL 1A (2 minutes per mark). Check the clock after every 10 questions: you should be at about 20, 40 and 60 minutes.

6. The traps in the wrong options

7. Routines by topic

• Circuits: redraw the circuit and combine resistors in steps. A parallel combination is smaller than its smallest resistor.
• Waves: draw the nodes and antinodes first. Open end: antinode. Closed end: node.
• Fields: draw field lines or arrows first. Equipotentials are at 90° to field lines. Watch the sign of potential and potential energy.
• Atoms and nuclei: count Z and A on both sides. The biggest energy gap gives the shortest wavelength (E = hc/λ).
• Relativity (HL): find the frame with the proper quantity. γ is always more than 1. Moving clocks run slow; moving rods are shorter. A relative speed is always less than c.
• Space–time diagrams (HL): axes x and ct; light at 45°; a steeper world line is slower; events simultaneous in S′ lie on a line parallel to the x′ axis.
• Stars (question 40): parallax d (pc) = 1 / p (arcsec); brightness b = L / (4πd²). Convert units at the end.

8. My 10 rules for Paper 1A

1. 40 questions, 1 mark each: 2 minutes per mark, 80 minutes for 1A (SL: 25 questions, 50 minutes).
2. Q1 is kinematics, Q40 is stars, and the paper goes A, B, C, D, E. Check your place.
3. Cover the options. Predict the answer first.
4. Underline numbers, units and “not”.
5. Always write an answer. A blank is 0; a guess has a chance.
6. Circle hard questions and do them in pass 2.
7. Draw: the circuit, the field lines, the standing wave, the space–time diagram.
8. Check units, size and direction.
9. Ratio question? Put in numbers 1 and 2.
10. Do not change an answer unless you can say exactly why it is wrong.

9. Small facts that cost marks

• Reactors: the moderator slows neutrons down; control rods absorb neutrons.
• Radiation: alpha is stopped by paper, beta by a few mm of aluminium; gamma has no charge and is not deflected by fields.
• Relativity: proper time is measured by one clock present at both events and is the shortest time; proper length is measured in the object’s rest frame and is the longest length.
• Stars: hot and bright stars are top left of the HR diagram; white dwarfs are hot but dim (bottom left).
• Interference: a path difference of a whole number of wavelengths gives a bright fringe; an odd number of half wavelengths gives a dark fringe.
• Induction: the induced emf opposes the change in flux linkage (Lenz’s law).

After every practice paper: keep a mistake log. For each wrong answer, write the topic, the kind of question and the reason (reading, formula, arithmetic, concept). Then fix the two most common reasons first.

Paper 1A practice papers

Each paper is complete and original, in the same order as the real paper (themes A to E), timed at 2 minutes per mark, and marked at the end with an explanation for every question. Choose your level.

The guide above comes from the HL papers. SL Paper 1A has the same theme order and the same kinds of question, with 25 questions instead of 40.

Practising one topic at a time? Every topic page also has its own Paper 1A set (for example A.1 Kinematics).

📄 Free PDF: 50 answers that get 0 marks, and what to write instead.