Four parts, one coherent lesson
Every part returns to one rule: measure many, then divide. The reaction-time error sits on the whole timing, so dividing by the count shares it out and shrinks it.
Lesson plan
A timed 45-minute sequence: a predict hook, the method, Numbered Heads Together, a pendulum practical, and an exit ticket. Objectives, vocabulary, examiner traps, differentiation and a timing and contingency note.
Worksheet and answers
Six original questions on the multiple-measurement method, the period from a count, and reaction time, with a full worked answer key.
Slides
Ten editable slides with accurate diagrams: the pendulum, why dividing shrinks the error, the method step by step, and a worked example.
Numbered Heads and results
Printable challenge cards for the cooperative task, plus a pendulum results sheet with an explain step.
Take the files
Editable formats, not locked PDFs. Adapt them to your set, your timing and your school's calendar.
Lesson plan
The 45-minute plan, with the measure many, then divide model, examiner traps and a timing and contingency note.
Download planWorksheet and answers
Six original questions with a full worked answer key and marking notes.
Download worksheetNumbered Heads and results
Print and cut: four challenge cards and the pendulum results sheet.
Download cardsSend learners to the lesson online
This bundle pairs with the student topic page Measuring length, volume, and time intervals, whose "measure many, then divide" section carries the interactive explanation of the multiple-measurement method. Set it for pre-reading, or open it on the board during the build.
One rule, made to stick
The lesson opens with a failure: timing a single swing by hand is hopeless, because reaction time is a large part of one short reading. From there it builds one rule, measure many then divide, and shows why it works: the start-and-stop error is about the same whether you time one swing or twenty, so dividing the total by the count shares it out.
Numbered Heads Together makes learners argue out a method for several small quantities, and the pendulum practical lets them feel the difference. Random call after the discussion keeps every learner accountable for the reasoning, not just the arithmetic.