Discovering New Shapes

Overview

Unit Title: Shapes Galore: 2D & 3D
Lesson Number: 3 of 6
Year Level: Year 1
Subject: Mathematics
Lesson Duration: 45 minutes
Class Size: 21 students
Teacher Location: Western Australia
Teaching Style: Mix of hands-on and worksheet-based activities
Curriculum Area: Measurement and Geometry — Shape
Australian Curriculum Reference:

• ACMMG022: Recognise and classify familiar two-dimensional shapes and three-dimensional objects using obvious features

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Lesson Title:

Introducing New 2D Shapes: Rhombus and Trapezium

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WALT (We Are Learning To):

• Identify and name 2D shapes: the rhombus and the trapezium
• Describe how many sides and vertices these shapes have
• Create rhombus and trapezium shapes using everyday materials

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Success Criteria:

By the end of the lesson, students will be able to: ✅ Say the names of the rhombus and trapezium correctly
✅ Identify these shapes in a group of other 2D shapes
✅ Count and describe the number of sides and corners (vertices)
✅ Use straws or sticks to create both a rhombus and a trapezium

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Materials Needed:

• Coloured plastic straws or pop sticks (at least 5 per student)
• Playdough or small blobs of blutack (to join corners)
• Shape posters (rhombus, trapezium, square, rectangle for comparison)
• Whiteboard & markers
• Printed “New Shapes Detective” worksheet (provided by the teacher or created ahead of time)
• A3 shape-matching mat (laminated if possible)
• Real-life objects in rhombus or trapezium shapes (e.g., a sign, a handbag tag, a folded napkin)

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Key Vocabulary:

• Shape
• Rhombus
• Trapezium
• Sides
• Vertices (corners)
• Same / different
• Equal / unequal

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Lesson Structure

1. Warm-Up Activity – Shape Snap Review (5 mins)

Purpose: Reinforce names of previously learned 2D shapes.
Instructions:

• Hold up flashcards (square, circle, triangle, rectangle) one at a time.
• Students shout the shape name and show it using their arms (e.g., triangle = hands above head making a point).
• “Mystery shape flashcard” (rhombus/trapezium) is shown at the end to introduce the new learning focus.

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2. Explicit Teaching – Meet the New Shapes (10 mins)

Focus: Rhombus and Trapezium

1. Show the rhombus:

   • Describe it: "A rhombus is like a pushed-over square. It has 4 equal sides and 4 corners.”
   • Show how it can look “tall” or “flat” depending on how it’s turned.
   • Emphasise: “All sides are the same length!”

2. Show the trapezium:

   • Describe it: “A trapezium is special—it has 4 sides, but only 2 sides are parallel. Some sides are longer than others!”
   • Demonstrate with hand gestures or cut-out shapes turned different ways.

3. Compare with rectangle/square using real object examples (use rotated shapes to show shapes can look different when turned).

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3. Guided Practice – Build the Shapes! (15 mins)

Hands-on activity with straws/pop sticks

Instructions:

• Students are given a small pile of straws or sticks and blutack/playdough blobs.
• Teacher models constructing a rhombus on the board or mat using four equal straws and connecting corners with playdough blobs.
• Students copy and build their own.
• Repeat for the trapezium, this time giving students varied lengths of straws and guiding them to form a trapezium (teacher demonstrates heavily here, as asymmetry may be challenging at first).

Discussion During Building:

• Are these sides the same length or different?
• How many corners did you make?
• Can you hold your shape over your head? How is it the same or different from a square?

Extension: Students try building both shapes flat on their desk, then pick them up and turn them—do they still look the same?

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4. Independent Task – “New Shape Detective” Worksheet (10 mins)

Students complete a worksheet with the following:

• Match the shape to the label (rhombus or trapezium)
• Count and write number of sides and corners
• Colour all the rhombuses red, trapeziums blue
• Circle which shapes have sides that are all the same

Teacher works with focus group for support as needed.

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5. Wrap-Up & Reflection (5 mins)

Think Pair Share:

• Give a partner a “shape clue” to guess: “It has 4 sides. All sides are the same. What is it?”
• One student volunteers to share their favourite new shape and why.

Revisit WALT:
🟢 Were we able to name two new shapes today?
🟢 Can we describe them by number of sides and corners?
🟢 Did we build them with materials?

Exit Ticket (Optional):
Each student draws a rhombus or trapezium on a mini whiteboard and labels it before lining up.

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Differentiation

Support:

• Use of pre-made shape cut-outs for tracing
• Partner-pairing for worksheet with peer tutor
• Teacher-led small group for shape building

Extension:

• Challenge students to create a picture using both rhombuses and trapeziums (e.g., build a robot or house)
• Identify real-world objects in the classroom that look like the new shapes

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Assessment Opportunities

• Observation during hands-on shape building: Are students forming the shapes accurately?
• Worksheet responses: Correct identification and features
• Exit tickets/mini whiteboards for quick formative check

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Teacher’s Notes

This lesson focuses heavily on hands-on discovery and kinaesthetic learning, perfect for Year 1 learners in Western Australia engaging with new geometry content. Keep it playful, reinforce vocabulary often, and encourage students to "think like shape detectives.” Display the new shapes on the wall to reinforce learning in future lessons and refer back in recap activities.