Q: What does Measurement and Uncertainty for IP Physics: From Sig-Figs to Spreadsheet Graphs cover? A: The 2026 SEAB syllabi has a huge component of experimental skills, data handling and spreadsheet analysis.
TL;DR - New syllabus = new marks. Quote instruments to the correct significant figures, report uncertainties as ±21 least-division, and round calculated quantities to the smallest-sf raw datum. Master absolute → fractional → percentage error conversions; propagate by addition for x / ÷, by sum of percentages for powers. Paper 4 (practical) now explicitly allows - and tests - spreadsheet skills: gradients, intercepts, "=STDEV.S( )" and trend-lines. Try the 20-s pendulum timing lab below; analyse your data with Sheets/Excel and you will have practised every assessed skill in one evening.
Need more structured drills? Follow the weekly diagnostics inside our IP Physics hub so measurement practice lines up with the rest of your upper-sec revision.
1 Why measurement & uncertainty just became high-stakes
Both O-level 6091 and A-level H2 (9478) syllabuses for 2026 list "handling experimental data, including spreadsheet processing" as an Assessment Objective worth up to 20 % of practical marks.
Specimen Paper 4 even states, "You may use a spreadsheet to process and analyse data.".
Private-tuition blogs warn that manual graph paper will be phased out, replaced by CSV uploads and Excel trend-lines.
2 Reading instruments & recording to the right sig-figs
2.1 Analogue versus digital
Instrument
Least division / resolution
Raw reading rule
Example
Metre rule
1mm
±0.5mm
42.0cm±0.05cm
Thermometer
1∘C
±0.5∘C
23.0∘C±0.5∘C
Digital stopwatch
0.01s
quote all decimals
12.37s
SEAB stipulates that "a measurement or calculated quantity must be accompanied by a correct unit, and calculated quantities should be given to the same number of significant figures as the least-sf raw datum."
For example, calculating R=V/I from 3 s.f. voltage and 2 s.f. current means your final R must be 2 s.f.
2.2 Sig-fig decision tree
Quote what the instrument shows - no truncation.
Intermediate steps: keep 1 extra sig-fig to suppress rounding drift.
Final line: match the least sig-fig among the raw inputs.
Worked example I=0.43A (2 s.f.), V=3.05V (3 s.f.) R=7.09Ω (calculator) → round to 2 s.f. →7.1Ω.
3 Absolute, fractional & percentage uncertainty
Symbol
Definition
Δx
Absolute uncertainty (same unit as x)
xΔx
Fractional uncertainty (no units)
xΔx×100%
Percentage uncertainty %
Rule-of-thumb: when you add/subtract, add absolute uncertainties; when you multiply/divide or raise to a power n, add percentage uncertainties and multiply by n.
Quick drill
A meter measures L=0.381±0.002m. Percentage uncertainty =0.3810.002×100=0.52%.
Community examples show the same propagation applied to pendulum g calculations.
4 Spreadsheet skills now examinable
SEAB's 2026 guide specifies that candidates must be able to **"process and analyse data using spreadsheet software, including calculating gradient and area under curves."
Practically, that means you should know how to:
Import a .csv file or type raw readings.
Use =AVERAGE(range) and =STDEV.S(range) for mean & sd.
Plot an XY Scatter, add a linear trend-line, tick Display equation and R².
Extract gradient/intercept directly from the equation box (e.g. y=3.21x+0.05).
Calculate % uncertainty of gradient with the built-in LINEST() function (advanced but examinable).
5 Mini-Lab: Timing a pendulum with your phone & Sheets
This 30-minute activity rehearses every skill the syllabus demands.
5.1 Setup
String, small metal nut, metre rule, phone timer/camera.
Measure L three times; take the mean length. Record to the nearest millimetre.
5.2 Data collection
Displace < 15° (small-angle).
Start timing on the first crossing; record 20 oscillations to reduce percentage timing error.
Repeat x 5 trials.
Trial
t20 / s
T=t20/20 / s
1
31.20
1.560
…
…
…
Reaction time of 0.2 s roughly halves when timing 20 periods versus one, cutting % uncertainty dramatically.
5.3 Spreadsheet crunch
In Sheets, enter L and corresponding T.
Create columns for T2 and lnT if you wish to test alternative models.
Plot T2 vs L; gradient m=g4π2.
Use =LINEST(T2_range, L_range, TRUE, TRUE) to obtain m and its standard error; convert to % uncertainty.
