Example · Maths · Year 6 · England

Measuring the Blackpool Tower

Danielle, Blackpool, Lancashire

Built by ALF Studio from exactly what each teacher typed, then changed the way that teacher teaches.

The unit as she left it

Drafted Oct 8 in 18 seconds · 5 changes since

Maths · Year 6 · 2 weeks

Measuring the Blackpool Tower

Driving question

How can we measure the height of Blackpool Tower without climbing it?

Standards

KS2 Maths: solve problems involving the relative…

solve problems involving the relative sizes of 2 quantities where missing values can be found by using integer multiplication and division facts

TAUGHT IN Week 1, activity 1; Week 1, activity 4; Week 2, activity 2; Week 2, activity 4; Week 1, activity 2ASSESSED BY Ratio and Relative Size

KS2 Maths: solve problems involving similar shapes…

solve problems involving similar shapes where the scale factor is known or can be found

TAUGHT IN Week 1, activity 3; Week 2, activity 1; Week 2, activity 3ASSESSED BY Similar Shapes and Scale Factors

Contains public sector information licensed under the Open Government Licence v3.0.

Overview

Pupils investigate how to measure tall seafront structures using shadow ratios and scale factors. After testing similar triangles with metre sticks in the playground, pupils estimate the height of Blackpool Tower, compare their findings against the known 158 metres, and design a seafront maths trail challenge card for Year 5 pupils to test.

Entry event

The teacher shows a photograph of Blackpool Tower alongside a standard metre rule. She asks the class how someone could find the exact height of the top spire without climbing it or using a giant tape measure. Pupils test their initial guesses against a toy figurine and its shadow on a desk lamp.

Need to know

How do our shadows change when our height changes?
What is a scale factor and how does it help us find missing heights?
How can we measure Blackpool Tower if we cannot touch the top?
What makes a good maths trail clue for younger pupils?

Week by week

Your lessons: 4 a week, 60 minutes.

Week 1

Understand ratio and scale factors by using shadows and similar triangles to find missing heights.

Measure pupil heights and outdoor shadow lengths in pairs to discover the constant multiplier between height and shadow.
· 1 lesson
Practise simplifying whole-number ratios using concrete counters and visual bar models before moving on to scale factors.
· 1 lesson
Practise solving missing length problems using similar right-angled triangles and whole-number scale factors on squared paper.
· 1 lesson
Apply shadow ratios to Blackpool Tower shadow data to calculate its height and compare results against the true 158 metres. Add the Comedy Carpet in front of the Tower as a second challenge: estimate its area by pacing and check against the published figure.
· 1 lesson

Supports

Provide dual-language ratio vocabulary mats for EAL pupils, pre-drawn scale diagrams on grid paper for pupils with SEND, and ask extension pairs to calculate percentage differences between their estimate and 158 metres. Give a worked example of the shadow ratio using a metre stick and a lamppost on the playground before anyone tries the Tower.

Deliverable

A completed calculation sheet showing the shadow ratio method used to estimate the height of Blackpool Tower.

Week 2

Create, critique, and finalise a seafront maths trail challenge card for Year 5 pupils.

Draft a seafront maths trail stop card that challenges Year 5 pupils to find a missing height using similar shapes and shadows.
· 1 lesson
Review partner draft cards using a checklist for clear instructions, correct scale factor steps, and an accurate answer key.
· 1 lesson
Revise and produce the final laminated trail cards, checking all scale diagrams and calculations.
· 1 lesson
Host a trial session where visiting Year 5 pupils test the trail cards around the school grounds and complete the challenges.
· 1 lesson

Supports

Provide sentence stems for clue wording for EAL pupils, scaffolded answer templates for pupils with SEND, and challenge extension pairs to include two-step scale factor clues.

Deliverable

A finished seafront maths trail challenge card with a worked answer key for Year 5.

Critique and revision

Week 2, lesson 1

Pairs swap draft trail cards during lesson 2 and use a three-point checklist to test whether the scale factor is clear, the clue is solvable, and the answer key matches.

Student reflection

Pupils complete an exit slip explaining how scale factor allowed them to measure an inaccessible object and identifying one improvement made after peer feedback.

Final product

What they make

Pupils create an illustrated seafront maths trail card that teaches Year 5 how to estimate the height of a local landmark using shadows and scale factors.

Options

Pupils choose which seafront structure to feature (such as the Tower, a shelter, or a lamp post) and whether to present clues using scale diagrams or ratio tables. Swap the scale drawing final task for an annotated photo task; we have no large paper and the photos keep the Tower in view.

Who sees it

Year 5 pupils and their form tutor test the cards during the final lesson of week 2.

Teams

Pairs assigned by the teacher, matching mixed-attainment partners.

Rubric3 rows · 4 levels

Criterion	beginning	developing	proficient	advanced
Ratio and Relative Size KS2 Maths: solve problems involving the relative… · individual	Struggles to find the multiplier between an object and its shadow without adult support.	Uses integer multiplication or division to find missing heights when the ratio is given.	Correctly calculates missing heights by finding and applying the ratio between heights and shadows.	Explains how the multiplier links object and shadow sizes and applies it accurately across varying measurements.
Similar Shapes and Scale Factors KS2 Maths: solve problems involving similar shapes… · team	Draws triangles that are not similar or misidentifies the scale factor.	Uses a given whole-number scale factor to find some missing sides on similar triangles.	Finds the correct scale factor between similar triangles and uses it to solve the height challenge.	Accurately constructs similar shapes and explains clearly how the scale factor proves the unknown height.
Mathematical Communication Collaboration · team	Trail card instructions are unclear or missing key measurements needed to solve the problem.	Trail card gives basic directions but requires verbal prompts for Year 5 pupils to follow the steps.	Trail card provides clear steps, accurate scale diagrams, and a fully worked answer key for Year 5.	Trail card guides Year 5 pupils independently with precise mathematical vocabulary, clear diagrams, and helpful hints.

Ratio and Relative Size

KS2 Maths: solve problems involving the relative… · individual

beginning

Struggles to find the multiplier between an object and its shadow without adult support.

developing

Uses integer multiplication or division to find missing heights when the ratio is given.

proficient

Correctly calculates missing heights by finding and applying the ratio between heights and shadows.

advanced

Explains how the multiplier links object and shadow sizes and applies it accurately across varying measurements.

Similar Shapes and Scale Factors

KS2 Maths: solve problems involving similar shapes… · team

beginning

Draws triangles that are not similar or misidentifies the scale factor.

developing

Uses a given whole-number scale factor to find some missing sides on similar triangles.

proficient

Finds the correct scale factor between similar triangles and uses it to solve the height challenge.

advanced

Accurately constructs similar shapes and explains clearly how the scale factor proves the unknown height.

Mathematical Communication

Collaboration · team

beginning

Trail card instructions are unclear or missing key measurements needed to solve the problem.

developing

Trail card gives basic directions but requires verbal prompts for Year 5 pupils to follow the steps.

proficient

Trail card provides clear steps, accurate scale diagrams, and a fully worked answer key for Year 5.

advanced

Trail card guides Year 5 pupils independently with precise mathematical vocabulary, clear diagrams, and helpful hints.

Materials

Metre sticks and 30-metre tape measures
Chalk for marking outdoor shadow lengths
Laminating pouches and card for trail stops
Photograph and factual height sheet for Blackpool Tower
check before use

Week 2, ready to teach

4 lessons · Built Oct 8 in 63 seconds

The week card on her unit reads: "Started from your changes to week 1: Added, Added a scaffold, Made it easier." Each lesson is a page for her, the task sheet is for the class, and ALF wrote the attachments the lessons hand out.

Week 2 · Lesson 1 of 4

Drafting the Seafront Trail Stop

Minutes60

Prep5 minutes

Parts4

BuiltOct 8

Checkpoint

Each pupil drafts a trail challenge draft card with clue text and a similar triangle diagram sketch, verified by teacher check.

Learning objective

Solve problems involving similar shapes where the scale factor is known or can be found.

I can identify matching sides between two similar right-angled triangles

I can design a trail card clue using shadow ratios to find an unknown height

Need to know

How do we write a clue so Year 5 can find a landmark height using shadows?

Sequence, 60 minutes47 of 60 minutes planned. The rest is yours.

Starter · 6 min

Display the class calculation from last week showing the shadow multiplier used for the Blackpool Tower. Review how pupil shadow lengths matched metre stick ratios at the same moment. Ask pairs to state what information a Year 5 pupil needs to calculate an unknown height.

Main · 10 min

Explain that two right-angled triangles are mathematically similar when matching angles are equal, meaning corresponding side lengths share the same scale factor multiplier. The ratio between an object height and its shadow length remains identical for all vertical objects measured in the same location at the same moment. Worked example, with example figures: a reference stick has height h = 1 metre and shadow s = 2 metres, while a seafront shelter casts shadow S = 8 metres; dividing 8 by 2 gives a scale factor of 4, so shelter height H equals 4 multiplied by 1, giving 4 metres.

Work time · 24 min

Hand out the draft trail stop template. Each pupil selects a seafront structure and designs a trail challenge draft card featuring clue instructions and a diagram sketch of two similar right-angled triangles. Both partners set a reference stick height figure of 1.0 metre, assign shadow measurements, and create the clue text. Circulate to check that pupils label reference object height h, reference shadow length s, structure shadow length S, and unknown landmark structure height H correctly.

Check and plenary · 7 min

Collect each pupil's trail challenge draft card to verify that the diagram pairs matching vertical heights and horizontal shadows correctly. Note pupils who mixed shadow and height lengths to run a ten-minute guided diagram check during the next lesson's starter. Next lesson pairs will review partner cards using a peer checklist.

Resources

makedraft trail stop template

haverulers

havesquared paper

Misconceptions

Pupils may compare reference stick height to landmark shadow length instead of corresponding sides; prompt them to highlight all vertical heights in red and all horizontal shadows in blue.

Adaptive teaching

Scaffold.Writing load: provide sentence stems for clue wording on vocabulary lists in home languages where the school has them, with pictures where it does not.

Challenge.Challenge pupils to write a two-step clue requiring Year 5 to calculate reference shadow length s first using half the stick height.

Next lesson

Next lesson pupils use the peer review checklist card to critique their partner's trail challenge draft card.

Her three edits

Each labeled by ALF after the save

What Danielle changed in the draft, in her own words, with the label ALF gave each change and the reason it suggested.

AddedWeek 1 · Activity 4Probably: challenge
Apply shadow ratios to Blackpool Tower shadow data to calculate its height and compare results against the true 158 metres. Add the Comedy Carpet in front of the Tower as a second challenge: estimate its area by pacing and check against the published figure.
The catalogue expected Made it local; ALF read it as Added and that label stands.
Added a scaffoldWeek 1 · SupportsProbably: support
Provide dual-language ratio vocabulary mats for EAL pupils, pre-drawn scale diagrams on grid paper for pupils with SEND, and ask extension pairs to calculate percentage differences between their estimate and 158 metres. Give a worked example of the shadow ratio using a metre stick and a lamppost on the playground before anyone tries the Tower.
Changed what students makeFinal productProbably: what I have
Pupils choose which seafront structure to feature (such as the Tower, a shelter, or a lamp post) and whether to present clues using scale diagrams or ratio tables. Swap the scale drawing final task for an annotated photo task; we have no large paper and the photos keep the Tower in view.
The catalogue expected Swapped; ALF read it as Changed what students make and that label stands.

Then she pressed Adapt this week

Week 1 · Too hard

Her note, with Too hard picked

“Ratio with decimal measurements lost half the class; add a lesson on simplifying whole-number ratios before the Promenade visit.”

ALF suggested. A simplifying whole-number ratios lesson added to Week 1.

Kept · RemovedMade it easier
Calculate the estimated height of tall school buildings using metre stick shadow ratios and integer multiplication.
Cutting the building estimation keeps the week to four lessons while making room for the foundational ratio lesson.
Kept · AddedMade it easier
Practise simplifying whole-number ratios using concrete counters and visual bar models before moving on to scale factors.
Grounding ratio in whole numbers gives students confidence before they apply it to shadow measurements on the Promenade.

She kept 2 of 2.

Then ALF built week 2. The week card reads “Started from your changes to week 1: Added, Added a scaffold, Made it easier.” Read the lessons.

Build one from your own idea

Type what you want to teach the way Danielle did. ALF drafts the unit, and you change whatever does not fit your class.

Start a unit All examples

Measuring the Blackpool Tower

Why it is here

What a school would ask first

The unit as she left it

Understand ratio and scale factors by using shadows and similar triangles to find missing heights.

Create, critique, and finalise a seafront maths trail challenge card for Year 5 pupils.

Week 2, ready to teach

Drafting the Seafront Trail Stop

Her three edits

Then she pressed Adapt this week

Build one from your own idea