If you're on Edexcel GCSE Combined Science (spec code 1SC0, often called the double award), there are 18 experiments you have to do in class and know for the exam. Edexcel calls them "core practicals". AQA calls theirs "required practicals". OCR calls theirs "PAGs". Same idea, different name on the tin.
This guide works through all 18 in the order Edexcel lists them, tells you which paper examines each one, and shows you what gets dropped if you're on Combined rather than the three separate GCSEs (1BI0 Biology, 1CH0 Chemistry and 1PH0 Physics). If you're still deciding between Combined and Triple, our Triple vs Double Science GCSE guide is probably the better starting point. If you've landed here but you're actually on AQA, use our AQA Combined Science required practicals guide instead.
This article was last checked against the Pearson Edexcel GCSE Combined Science (1SC0) specification on 14 October 2026. Specs do shift, so cross-check the current Pearson page before relying on any specific detail.
Combined Science (1SC0) is the double-award GCSE: you come out with two grades on one certificate, anywhere from 9-9 down to 1-1. On the Triple route you sit three separate GCSEs with 24 core practicals in total: 8 Biology, 8 Chemistry, 8 Physics. The side-by-side comparison is further down.
All 18 Edexcel core practicals
The table below is every core practical on the 1SC0 spec in topic order, using Edexcel's own spec reference numbers. Each practical is written into the spec as a numbered point in italics, with the line "students must carry out all 18 of the mandatory core practicals listed below" sitting above the list. Each paper runs for 1 hour 10 minutes, is worth 60 marks and makes up 16.67% of your overall grade. Papers 1 and 2 are Biology, 3 and 4 are Chemistry, 5 and 6 are Physics.
| Spec ref | Core practical | Science | Paper |
|---|---|---|---|
| 1.6 | Investigate biological specimens using microscopes, including magnification calculations and labelled scientific drawings | Biology | 1 or 2 |
| 1.10 | Investigate the effect of pH on enzyme activity | Biology | 1 or 2 |
| 1.16 | Investigate osmosis in potatoes | Biology | 1 or 2 |
| 6.5 | Investigate the effect of light intensity on the rate of photosynthesis | Biology | 2 |
| 8.11 | Investigate the rate of respiration in living organisms | Biology | 2 |
| 9.5 | Investigate the relationship between organisms and their environment using field-work techniques, including quadrats and belt transects | Biology | 2 |
| 2.11 | Investigate the composition of inks using simple distillation and paper chromatography | Chemistry | 3 |
| 3.6 | Investigate the change in pH on adding powdered calcium hydroxide or calcium oxide to a fixed volume of dilute hydrochloric acid | Chemistry | 3 |
| 3.17 | Investigate the preparation of pure, dry hydrated copper sulfate crystals, starting from copper oxide | Chemistry | 3 |
| 3.31 | Investigate the electrolysis of copper sulfate solution with inert electrodes and copper electrodes | Chemistry | 3 |
| 7.1 | Investigate the effects of changing conditions on rates of chemical reactions (gas production with HCl and marble chips; colour change with sodium thiosulfate and HCl) | Chemistry | 4 |
| 2.19 | Investigate the relationship between force, mass and acceleration by varying masses added to trolleys | Physics | 5 |
| 4.17 | Investigate the suitability of equipment to measure the speed, frequency and wavelength of a wave in a solid and a fluid | Physics | 5 |
| 5.9 | Investigate refraction in rectangular glass blocks in terms of the interaction of electromagnetic waves with matter | Physics | 5 |
| 10.17 | Construct electrical circuits to investigate potential difference, current and resistance for a resistor and filament lamp, and test series and parallel circuits | Physics | 6 |
| 14.3 | Investigate the densities of solids and liquids | Physics | 6 |
| 14.11 | Investigate the properties of water: determine the specific heat capacity of water and obtain a temperature–time graph for melting ice | Physics | 6 |
| 15.6 | Investigate the extension and work done when applying forces to a spring | Physics | 6 |
Count it up: six Biology, five Chemistry, seven Physics, 18 total. Topic 1 (Key concepts) sits across both Biology papers, so you don't know in advance whether you'll see the microscope question, the enzyme question or the osmosis one on Paper 1 or Paper 2. In Chemistry, Topic 3 (Chemical changes) is the practical-heavy one, with three sitting on Paper 3. In Physics, Topic 14 (Particle model) has two of its own.
How practical skills are assessed
There's no separate practical exam. Practical-skills questions are stitched into all six written papers. Most of them fall under AO2 (apply knowledge and understanding, which is 40% of the grade) and AO3 (analyse, interpret, evaluate, suggest improvements, which is 20%). AO1 (recall and understanding) is the other 40%.
Schools have a job to do here too. Centres have to submit a Practical Science Statement to Pearson by 15 April of the exam year, confirming you've done all 18. If a school doesn't submit it, Pearson treats that as malpractice. You won't ever need to think about it as a student, but it's the reason your teachers get a bit twitchy about getting through every practical, even the ones that fall on a dodgy Friday afternoon.
The exam questions themselves look the way practical questions always look: describe the method, name the variables, explain the results, suggest an improvement. The Edexcel-specific phrasing to watch for is "evaluate the method" (which wants a weakness plus a specific improvement) and "explain the pattern in the results" (which wants scientific reasoning, not just "the line goes up then flattens").
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Combined vs Triple reconciliation
Combined (1SC0) drops six core practicals compared to the three separate Edexcel GCSEs. Triple adds up to 8 + 8 + 8 = 24. Combined comes out at 6 + 5 + 7 = 18. The drops aren't even across the sciences: two from Biology, three from Chemistry, one from Physics. Edexcel builds the drops around topics and sub-topics that only appear on the separate specs.
| Science | Dropped from Triple → Combined | Topic area dropped |
|---|---|---|
| Biology | 1.13B Use chemical reagents to identify starch, reducing sugars, proteins and fats (food tests) | Topic 1: Key concepts in biology |
| Biology | 5.18B Investigate the effects of antiseptics, antibiotics or plant extracts on microbial cultures | Topic 5: Health, disease and the development of medicines |
| Chemistry | 5.9C Carry out an accurate acid-alkali titration | Topic 5: Separate chemistry 1 |
| Chemistry | 9.6C Identify the ions in unknown salts using tests for the specified cations and anions | Topic 9: Separate chemistry 2 |
| Chemistry | 9.28C Investigate the combustion of alcohols (ethanol, propanol, butanol, pentanol) by measuring temperature rise in a known mass of water | Topic 9: Separate chemistry 2 |
| Physics | 5.19P Investigate how the nature of a surface affects the amount of thermal energy radiated or absorbed | Topic 5: Light and the electromagnetic spectrum |
If you're on Combined, don't revise titration, ion identification tests, combustion of alcohols, food tests, microbial culture practicals or thermal-radiation surface experiments as core practicals. They aren't on your spec. Topics 5 and 9 in Chemistry are the obvious "separate only" chunks, plus the deeper content inside Biology Topics 1 and 5 and Physics Topic 5. Some of the underlying science (rates, equilibria, radiation and absorption) still crops up in Combined content, just not as a dedicated core practical you'd be examined on.
Study tips for the 18 practicals
Reading through the method the night before isn't enough. Core practical questions test whether you can think like a scientist, not whether you can recite a recipe from memory.
For each practical, try writing the method out from scratch, then check it against your notes or a Cognito video. The steps you forgot are the exact steps that would have lost you marks. Pay attention to the fiddly bits Edexcel loves to probe: controlling the volume and temperature of the solution in the osmosis experiment, naming the specific buffer you'd use for the enzyme practical, calculating Rf as distance travelled by substance divided by distance travelled by solvent, blotting potato cylinders before weighing them, using a respirometer with soda lime to absorb carbon dioxide.
Practise drawing a proper results table, with the independent variable in the left column, units in the headers (not next to every value) and consistent decimal places. Edexcel often gives you a half-finished table and asks you to complete it, and marks come from getting those conventions right.
Sketch the shape of the graph you'd expect for each one. Light intensity against rate of photosynthesis: a curve that rises then plateaus. Force against extension of a spring: a straight line through the origin, then it kinks at the limit of proportionality. Temperature against time while ice melts: a plateau while the ice is melting. Even if you can't nail the explanation, correctly plotted and labelled axes pick up marks.
The most useful thing to do is work through past paper questions on each core practical. Edexcel recycles phrasing year on year, and the mark schemes are the clearest guide to the exact words they want.
When the question asks you to suggest an improvement, Edexcel wants a specific change plus the specific reason it works. "Repeat the experiment" is half an answer. "Repeat and calculate a mean to reduce the effect of random error" is a full answer.
How Cognito helps
Our Edexcel GCSE Combined Science courses cover all 18 core practicals through short video lessons, worked examples and exam-style questions. Each practical gets its own lesson that walks you through the method, the variables, the results and the exam language. Jump into the Combined Science Biology course, the Combined Science Chemistry course or the Combined Science Physics course and tick your way through the whole spec.
If you're looking at how to fit practicals into your wider revision, our how to revise for GCSE Science guide walks through paper structure, timing and how to spread the practicals across a term.
