💡 Lesson Overview
This lesson introduces thirds — three equal parts of a whole. This is a conceptual leap because dividing into 3 parts is less intuitive than dividing into 2 or 4. Students explore different strategies to create thirds, discovering that equal shares may look different but must contain the same number of bricks.
The focus of this lesson is:
- understanding that thirds mean three equal shares of a whole
- discovering that equal shares may look different
- exploring different strategies to create three equal parts
- checking fairness by counting bricks, not by shape
- explaining reasoning in complete sentences
- comparing ways of dividing a whole into three parts
- supports purposeful decision-making when choosing a model
🧠 Core Concept (Brickit Fractions Definition):
Three equal parts (thirds) each contain the same number of bricks. The shapes may be different — fairness is about equal amounts.
🟠 Important Note:
Many LEGO models do NOT split neatly into thirds. This is part of the inquiry. The goal is not perfection — the goal is to understand that thirds = 3 equal amounts.
Designed for Grades 1–2, with extensions for Grade 3. Aligned with Common Core (2.G.A.3), Cambridge Primary (Stage 1–2), and IB PYP.
Part of the Brickit approach — transforming existing LEGO® bricks into meaningful learning.
🎯 Today's Goal for Students
👩🏫 What to tell your students at the start of the lesson:
"Today we are learning about thirds — three equal parts. We will divide our model into three equal parts. Each part has the same number of bricks, even if they look different."
💡 This simple statement helps students understand the purpose of the lesson and makes their actions more meaningful and focused.
🎯 Learning Goals
Thirds Understanding
Understand that thirds mean three equal shares of a whole
Discover that equal shares may look different
Strategy Exploration
Explore different strategies to create three equal parts
Compare ways of dividing a whole into three parts
Fairness & Equality
Check fairness by counting bricks, not by shape
Recognize that shapes may differ but amounts must be equal
Mathematical Language
Explain reasoning in complete sentences
Use terms: thirds, equal, share, whole, part
Representation
Represent thirds in drawings and words
Describe strategies and discoveries
Problem Solving
Adjust models when totals don't divide evenly
Find multiple solutions to the same problem
🧠 Skills Developed
| Domain | Focus in this Lesson |
|---|---|
| Mathematics | Thirds, three equal parts, fractions foundation |
| Problem Solving | Exploring strategies, adjusting models, finding solutions |
| Cognitive Skills | Reasoning about thirds, comparing strategies |
| Communication | Using fraction vocabulary, explaining strategies |
| Collaboration | Working as a team to explore thirds |
| Representation | Building mini-models, drawing thirds |
🧰 Teacher Preparation
Materials per team (typically 2–4 students; up to 5–6 if needed)
200–400 mixed LEGO® bricks
1 device with Brickit App for Schools
Printed Student Recording Sheet (1 per student)
Teacher Observation Checklist
Before class
Mentally prepare multiple sample strategies:
• break the whole into loose bricks
• build three mini-models
• divide by colour groups
• divide by brick-count
🟠 Teacher Message to Self:
Remind yourself: many LEGO models do NOT split neatly into thirds. This is part of the inquiry.
The goal is not perfection. The goal is to understand that thirds = 3 equal amounts.
This lesson also supports strategy awareness — children observe how others sort, count, and group materials and may choose strategies that work for them.
This lesson encourages purposeful model choice — students learn to select a model that interests them and is appropriate for the time available.
📝 Teacher Notes — Why We Build First
Every Brickit Math lesson begins with: Sort → Scan → Choose → Build.
This routine:
- reduces frustration by organising the pile
- helps students understand what pieces they have
- allows them to make meaningful choices
- builds motivation and ownership
- creates a concrete model that becomes the foundation for mathematical thinking
- strengthens problem solving when substitutions are needed
- supports tactile and visual learners
- aligns with inquiry-based mathematics (Common Core, PYP, Cambridge)
Building is not optional: it is the engine that drives mathematical exploration in this lesson.
📄 Student Recording Sheet
Print this worksheet for each student or group:
Building with Thirds – Lesson 2.3
Name: __________________ Date: ____________
My whole has ______ bricks.
My thirds:
Part 1 has ______ bricks.
Part 2 has ______ bricks.
Part 3 has ______ bricks.
My thirds are equal because ________________________.
My drawing of thirds:
(draw 3 equal shares)
Something I discovered today: ________________________
📘 Lesson Flow
🧺 Sort the Pile
Duration: 5–8 minutes
👩🏫 Instructions
"Sort your bricks by an attribute. Today we will try to take one whole model and split it into three fair shares. Fair means each share has the same number of bricks."
"If you choose colour, put similar shades together — all blues in one group, all yellows in another. No need for exact shade matching."
"You can sort by colour families, shape, height, or number of studs. Choose what makes sense to you."
"Do not aim for perfect sorting. If bricks are connected, leave them together."
👧👦 What You Need to Do
- Sort by chosen attribute (colour families, shape, height, or studs)
- Do not aim for perfect sorting
- If you see a sorting strategy you like, try it
👩🏫 Teacher Focus
- Reinforce: Sorting helps us organise for fair sharing
- Remind: Fairness is about amount, not appearance
- Accept any reasonable sorting strategy
🟦 Teacher Tip
Sorting is a warm-up, not a requirement. It helps organise materials and activates attention. Connected bricks can stay together. Multi-colour bricks can go in mixed groups or by dominant colour — both choices are fine.
🔁 If students struggle…
- Remind: "Similar colours go together — no need for exact matching."
- If bricks are hard to separate: "Leave them together — that's fine."
- If a student is stuck: "Try sorting by shape instead."
📝 Teacher Notes
- Sorting is not required for the Brickit scan and does not need to be exact.
- If some bricks are tightly connected, leave them together — perfection is not required.
- If a brick has more than one colour (windows, wheels), place it in a mixed-colour group or choose the dominant colour. Either choice is acceptable.
- Sorting helps children notice attributes, organise materials, and prepare for counting. Its purpose is cognitive activation, not correctness.
- Children may use different sorting strategies. Encourage noticing how others work and trying new strategies. Strategies are optional — accuracy in counting is the goal.
📷 Scan & Choose a Model
Duration: 5–8 minutes
👩🏫 Instructions
"Spread your bricks into one flat layer — one brick thick. This helps Brickit see everything."
"Now scan with the Brickit App. Look at the models it suggests."
"Select a model. This will be your whole that we divide into thirds."
"Choose a model your team likes, can build, and can build quickly — about 5–7 minutes."
"Brickit recognises shape and size, not colour. You can use any colours you have. Substitutions are correct and encouraged."
📋 Model Selection Rule
A model is "just right" if:
- students LIKE it
- they CAN build it (not too many tiny parts)
- they can build it QUICKLY (5–7 minutes)
- approx. 8–15 bricks (if visible in app)
- simple shape, no rare bricks
- substitutions are expected
- can be divided into thirds (numbers divisible by 3 work best)
👧👦 What You Need to Do
- Spread bricks on a flat surface (one layer thick)
- Scan with the Brickit App
- Look at suggested models
- Choose a model that feels "just right"
👩🏫 Teacher Focus
- Ensure each team makes their own choice
- Reinforce: Every choice is valid
- If your Brickit shows piece-count, guide toward 8–15 bricks
🟦 Teacher Tip
Children choose by interest first. Guide gently toward models they can build in 5–7 minutes: one clear object, few tiny pieces, visually simple.
🟠 Teacher Note
Choose a model with brick total divisible by 3 when possible. If not divisible, students will need to add/remove 1–2 bricks.
Teacher says: "If your total is tricky to share, that's part of the challenge. You can adjust your model to make fair thirds."
🔁 If students struggle to choose…
- Remind the three rules: LIKE it, CAN build it, QUICK to build
- Help find a simpler model if current choice is too complex
- Say: "If it feels 'just right', that's perfect."
⚠️ If students struggle to build
- Switch to a simpler model
- Freeze the build "as is" and move to math
- Move to math even if model is unfinished — the goal is mathematical reasoning, not perfect building
📝 Teacher Notes
- The colour of the suggested Brickit model does not matter. Children may build using any available colours.
- If a piece is missing, students should choose a similar size/shape — this is correct problem-solving.
- If your Brickit version shows piece-count, aim for 8–15 bricks. If not, guide using visual simplicity.
- Sorting and rebuilding do not need to be perfect. The goal is mathematical reasoning, not precision.
🧱 Build the Whole
Duration: 5–8 minutes
🧠 Strategy Awareness
You may count in different ways (ones, groups of 2, groups of 5). Notice how others work and try new strategies. Strategies are optional; accuracy is the goal.
👩🏫 Instructions
"Now build your chosen model. This will be your whole."
"How many bricks are in your whole? Choose a counting strategy that helps you stay accurate."
"Is this number easy or hard to share into 3 parts?"
"Write your number on your Recording Sheet."
👧👦 What You Need to Do
- Build the chosen model collaboratively
- Count total bricks in the model
- Choose a counting strategy (ones, groups of 2, groups of 5)
- Record the total on Recording Sheet
👩🏫 Teacher Focus
- Ask: "How many bricks are in your whole?"
- Ask: "Is this number easy or hard to share into 3 parts?"
- Reinforce: This is the "whole"
- Observe counting strategies used
🟠 Teacher Note
If total brick count is not divisible by 3, guide students:
- remove 1 brick
- or add 1 brick
- or choose a different model
This reduces frustration and builds mathematical reasoning.
🟦 Teacher Tip
Substitutions are correct and encouraged. If a team can't find the exact piece, they should use a similar one. This is mathematical problem-solving, not a building test.
🔁 If students struggle…
- If building takes too long: "Freeze your model as is and move to counting."
- If count seems wrong: "Try counting again using a different method."
- If team is stuck: "Ask another team for help finding pieces."
📝 Teacher Notes
- Brickit recognises shape and size, not colour. Substitutions are expected and correct.
- The model does not need to match the instructions exactly. Approximate matches are fine.
- If building is taking too long, it's acceptable to move to the math part with an incomplete model.
🔍 Explore: "What makes a third?"
Duration: 5 minutes
👩🏫 Instructions
"Before we divide, let's discuss: What does 'three equal parts' mean?"
"Do the parts need to be the same shape? How can we check fairness?"
"Thirds = 3 equal shares = each has the same number of bricks."
"Equal does not mean identical."
👧👦 What You Need to Do
- Discuss: What does "three equal parts" mean?
- Discuss: Do the parts need to be the same shape?
- Discuss: How can we check fairness?
- Share ideas with the class
👩🏫 Teacher Focus
- Write key sentence on board: "Thirds = 3 equal shares = each has the same number of bricks."
- Reinforce: Equal does not mean identical
- Ensure students understand: fairness is about number, not shape
🟦 Teacher Tip
Conceptual understanding comes first. Students need to understand what "thirds" means before they can divide successfully.
🔁 If students struggle…
- If students think parts must look the same: "Equal means same number of bricks, not same shape."
- If fairness is unclear: "We check fairness by counting bricks, not by looking at shapes."
🔍 Try Strategy 1: Break into Loose Bricks
Duration: 10 minutes
👩🏫 Instructions
"Break your model into loose bricks. Make 3 piles."
"Count bricks in each pile. Adjust to make piles even."
"This is the simplest and most reliable strategy for thirds."
👧👦 What You Need to Do
- Break the model fully or partially into loose bricks
- Make 3 piles of bricks
- Count bricks in each pile
- Adjust to make piles even
- Record brick counts
👩🏫 Teacher Focus
- Ask: "How many bricks should each part have?"
- Ask: "Are your piles equal now?"
- Ask: "What did you change to make them equal?"
- Support students who struggle to make equal piles
🟦 Teacher Tip
Breaking into loose bricks is the simplest strategy. Students can easily count and adjust to make equal piles.
🔁 If students struggle…
- If piles are unequal: "Count bricks in each pile. Do they all match?"
- If students can't make 3 piles: "Start with all bricks in one pile, then split into 3."
- If total doesn't divide evenly: "Try adding or removing 1–2 bricks to make a number divisible by 3."
🔍 Try Strategy 2: Build 3 Mini-Models
Duration: 8–10 minutes
👩🏫 Instructions
"Now rebuild your shares into 3 small models. Each mini-model should have the same number of bricks."
"Shapes may differ — only brick count matters."
👧👦 What You Need to Do
- Rebuild your shares into 3 small models
- Count bricks in each mini-model
- Adjust to ensure equality
- This develops: representation, creativity, spatial reasoning, attribute language
👩🏫 Teacher Focus
- Ask: "Do your three mini-models have the same number of bricks?"
- Ask: "Do they look the same or different?"
- Ask: "Are they still equal?"
- Reinforce: Shapes may differ — only brick count matters
🟦 Teacher Tip
Building mini-models develops spatial reasoning. Students see that equal shares can look different — this is a key understanding for fractions.
🔁 If students struggle…
- If mini-models are unequal: "Count bricks in each mini-model. Do they all match?"
- If students worry about different shapes: "Different shapes are fine — only brick count matters."
- If building takes too long: "You can keep them as piles if that's easier."
⚖️ Comparison & Reasoning
Duration: 3–5 minutes
👩🏫 Instructions
"Compare both strategies. Discuss:"
- "Which strategy was easier: piles or mini-models?"
- "What was difficult about thirds?"
- "Why is dividing into 3 parts different from dividing into 2 or 4?"
- "What did you discover about fair sharing?"
"Not all wholes split naturally into thirds. We need to adjust the model or re-build to make equal shares."
👧👦 What You Need to Do
- Compare both strategies
- Discuss which was easier and why
- Explain what was difficult about thirds
- Share discoveries about fair sharing
👩🏫 Teacher Focus
- Reinforce: Not all wholes split naturally into thirds
- Celebrate clear explanations
- Support students who need help articulating reasoning
🟦 Teacher Tip
Comparison builds understanding. Students see that dividing into 3 parts is more challenging than dividing into 2 or 4 parts.
🔁 If students struggle…
- If explanation is unclear: "Tell me: which strategy was easier? Why?"
- If students can't compare: "Think about: was it easier to make piles or mini-models?"
💭 Reflection & Recording
Duration: 5 minutes
👩🏫 Instructions
"Complete your Recording Sheet with all your work."
"What strategy helped you divide into thirds today?"
"Did you try a new strategy or learn from someone else?"
👧👦 What You Need to Do
- Write number of bricks in each third
- Write explanation of fairness
- Draw thirds
- Write one discovery
- Reflect on division strategies you used
👩🏫 Teacher Focus
- Collect evidence of learning through Recording Sheets
- Use observation checklist: counts correctly, equal shares verified, reasoning clear, collaboration effective
- Take photos of models if helpful
- Quick interviews: "Tell me about your thirds."
🟦 Teacher Tip
Reflection builds metacognition. Students think about their own thinking and learn from others' strategies.
🔁 If students struggle…
- If Recording Sheet is incomplete: "Check your brick counts and thirds — make sure everything is recorded."
- If reflection is unclear: "Tell me: how did you make thirds?"
🧩 Differentiation
Emerging Learners (Grade 1)
- Work only with piles (Strategy 1)
- Teacher chooses whole with 9 or 12 bricks
- Focus on counting equal amounts
Developing Learners (Grade 2)
- Complete both strategies
- Build simple mini-models
- Explain fairness in sentences
Advanced Learners (Grade 2–3)
- Try to create thirds from a TOTAL that is NOT divisible by 3 (for example 10 → remove 1 brick → 9 → thirds)
- Explain why adjustments are needed
- Compare thirds from different wholes
🧮 Teacher Observation Checklist
Use during circulation.
| Skill | Evidence | Check |
|---|---|---|
| Whole understanding | Counts bricks in whole | ☐ |
| Partitioning | Creates 3 piles with equal amounts | ☐ |
| Rebuilding | Builds 3 mini-models with equal amounts | ☐ |
| Reasoning | Explains fairness using brick count | ☐ |
| Comparison | Describes strategies and differences | ☐ |
| Representation | Draws thirds | ☐ |
| Collaboration | Works effectively in the group | ☐ |
🌿 Extension Ideas
Explore Odd Totals
Explore: "Can we divide 14 bricks into 3 equal parts? Why or why not?"
Fraction Museum
Build a fraction museum of different thirds
Compare Totals
Compare: "Is it easier to share 12 or 15? Why?"
Colour Challenge
Make thirds using only bricks of one colour
📚 Curriculum Alignment
| Framework | Standards |
|---|---|
| Common Core (US) | 2.G.A.3 — partition shapes into 2, 3, 4 equal shares; MP1 — make sense of problems; MP2 — reason quantitatively; MP3 — explain thinking |
| Cambridge Primary (Stage 1–2) | M2.3 — equal shares, thirds |
| IB PYP Mathematics | "Inquiry through hands-on building." "Parts/whole relationships." |