Shape Detectives

Overview

Students use an MGI-style sequence of launch, explore, discuss and reflect to investigate familiar three-dimensional objects. They identify surfaces, sort objects by observable features and use the term face accurately when explaining their thinking.

Learning intentions

Students will:

• describe features of familiar three-dimensional objects
• identify the surfaces, or faces, of an object
• sort objects according to an obvious feature
• use the mathematical term face when describing 3D objects

Success criteria

• I can identify the surfaces of a 3D object.
• I can sort familiar 3D objects according to a feature I can see.
• I can use the word face correctly when describing a 3D object.
• I can explain why an object belongs in a particular group.

Curriculum links

• Mathematics — represent and describe the positions and features of objects in familiar locations.
• Mathematics — use mathematical language to describe, compare and classify objects according to observable features.
• Mathematics — communicate mathematical thinking by representing, explaining and justifying choices.
• Mathematical problem-solving and reasoning — notice attributes, make comparisons and explain a sorting rule.

Lesson structure (50 minutes)

1. 0–5 min · Launch: Mystery object. Teacher places a hidden cube, ball and cylinder in a bag and reveals one object at a time while displaying the mystery-object hook; students quietly predict which objects might have flat surfaces and share what they notice with a partner.

2. 5–13 min · Connect and model. Teacher displays a cube and explains that a solid object is three-dimensional because it has length, width and height; the teacher touches one flat surface and introduces the word face, then models a sentence such as “A cube has flat faces.” Students handle a classroom object, point to a face and repeat the sentence using the object’s name.

3. 13–25 min · Explore in groups. Teacher places students in groups of four with a mixed collection of safe 3D objects and displays the explore instructions and object photographs; students take turns being the holder, describer, sorter and reporter while they investigate flat or curved surfaces, surfaces that are the same shape, and objects that roll or do not roll.

4. 25–34 min · Sort and record. Teacher asks each group to choose one obvious sorting rule and checks that the rule can be seen or tested; students sort their objects into two or more groups, then complete the 3D object sorting worksheet by drawing or naming objects, circling faces and recording their rule using the sentence stem “I sorted the objects by ___ because ___.”

5. 34–43 min · Share and compare. Teacher invites groups to present their sort and uses the sorting discussion prompts to compare rules, asking “Could this object belong in another group?” and “How do you know this is a face?” Students explain their decisions, listen for similarities and differences, and revise a sort if another rule is more useful.

6. 43–50 min · Reflect and assess. Teacher displays the final challenge and reflection prompt and gives each student a small object or object photograph; students identify one face, complete the oral or written sentence “A ___ has ___ face/faces,” and explain one sorting rule before packing away.

Resources

• the 3D object investigation deck
• the 3D object sorting worksheet
• Collections of familiar 3D objects: cubes, rectangular prisms, cylinders, cones, spheres and triangular prisms
• Hoops, trays or large sheets of paper for sorting groups
• Small labels or sticky notes
• Pencils, crayons and clipboards
• One mystery bag
• Optional document camera or interactive whiteboard

Assessment

• During modelling, ask individual students to point to a face and distinguish a flat face from a curved surface.
• During group work, listen for correct use of face, evidence-based sorting rules and explanations such as “It belongs here because it has flat faces.”
• Use the worksheet and final challenge to record whether each student can identify a face, sort by an observable feature and explain their rule.

Differentiation

• Support students with real objects before photographs, repeated modelling, gesture cues and the sentence stems “I can see…” and “I sorted by…”.
• Provide a smaller collection of clearly contrasting objects, such as a ball, box and can, for students needing reduced choice.
• Pair EAL/D learners with supportive peers and display labelled images for object, face, flat, curved, roll and does not roll.
• Extend confident students by asking them to sort the same collection in two different ways, explain whether a sphere has a face, or find an object that fits more than one group.