PDO & Uncertainty Masterclass for H2 Chemistry Paper 4

Q: What does the PDO & Uncertainty Masterclass deliver?
A: Ready-to-use spreadsheet layouts, graphing routines, and uncertainty workflows that let H2 candidates present Paper 4 data with the precision SEAB’s 2026 syllabus demands.

TL;DR
PDO feeds directly into ACE scores.
Build structured tables, automate calculations, and quote uncertainties properly so every Paper 4 dataset stands up to moderator scrutiny.

Status: SEAB H2 Chemistry (9729, first exam 2026) syllabus last checked 2025-11-29 (PDF last modified 2024-07-17). Paper 4 remains 2 h 30 min, 55 marks, weighting 20 %, with Planning at 5 % and MMO/PDO/ACE at 15 % combined.

1 | Why PDO & uncertainty carry weight

• The 2026 H2 Chemistry Practical Assessment (SEAB 9729) emphasises accurate observation/measurement (MMO) and disciplined data presentation (PDO) before candidates interpret results (ACE); Paper 4 weights Planning at five percent and MMO/PDO/ACE at fifteen percent combined.
• The Mathematical Requirements section expects competence with linear graphs, logarithms, and error handling-skills that must show up in your tables and write-ups.
• Strong PDO shortens ACE because you already have tidy calculations and quantified uncertainty to discuss.
• The 9476 Paper 4 specimen released for the 2026 sitting reinforces this-each question provides structured tables and asks candidates to propagate uncertainties, so practising the spreadsheet + PDO routines here keeps you aligned with the official mark scheme.

2 | Core spreadsheet toolkit

• Structure: Use Raw Data, Processed, and Uncertainty tabs. Keep units in header rows (Volume / cm³).
• Formulas: Deploy named ranges (e.g., NaOH_Molarity) and functions such as =AVERAGE, =STDEV.S, =SLOPE, =INTERCEPT, and =FORECAST.LINEAR.
• Automation tips: Lock cell references ($B$