Surface Area Presentation Prep

Overview

In this seventh lesson of the eight-lesson unit, students finalize the exterior surface-area calculation for their similar-shape model and prepare a concise mathematical presentation. They apply prior learning about scale factor, nets, composite solids, and surface area while revising both construction accuracy and mathematical communication.

Learning intentions

Students will:

• identify every exposed face on a composite model and organize the information in an inventory;
• calculate total exterior surface area using appropriate formulas and correct treatment of shared faces;
• communicate scale factor, similar shapes, nets, composite solids, and surface-area reasoning;
• use feedback from a four-level rubric to improve a model and its explanation.

Success criteria

• I can list every exposed face and explain why shared internal faces are not included.
• I can show formulas, substitutions, calculations, and square units clearly.
• I can explain how the scale factor and similar shapes relate to my model.
• I can rehearse a focused 2–3 minute presentation using mathematical vocabulary.

Curriculum links

• Shape and Space — investigate and apply surface-area strategies for composite three-dimensional objects.
• Shape and Space — analyze similarity and use scale factors to relate corresponding dimensions.
• Mathematical Processes — communicate mathematical ideas using diagrams, symbols, calculations, and oral explanations.
• Mathematical Processes — solve problems, make connections, and verify the reasonableness of results.

Lesson structure (30 minutes)

1. 0–4 min · Reconnect and focus. Teacher opens the introduction and learning-intention slides and displays a model or photograph with the prompt, “Which faces count toward the outside surface area?” Students briefly identify visible faces and recall that shared faces become internal when solids are joined.

2. 4–9 min · Model the checkpoint. Teacher uses the worked surface-area example to demonstrate an exposed-face inventory: label each face, record dimensions and shape, select a formula, calculate area, and total the results in square units. Emphasize that a face shared by two joined solids is excluded, and model a reasonableness check. Students annotate their own project notes and ask clarifying questions.

3. 9–18 min · Complete Checkpoint 4. Teacher distributes the exposed-face inventory and calculation sheet and circulates, verifying each group’s face inventory and calculations before students proceed. Students work individually or with their project partner to list exposed faces, calculate each area, show substitutions and units, identify shared faces, and write a short explanation connecting the result to the model’s dimensions and scale factor. Teacher initials or dates the completed checkpoint.

4. 18–23 min · Rubric revision. Teacher returns to the four-level rubric and revision prompts and asks students to check accuracy, completeness, clarity, and presentation readiness. Students compare their work with the rubric, correct errors, improve labels or diagrams, and make one specific construction or communication revision. Partners use the prompt, “One strength is… One improvement is… because…”

5. 23–28 min · Presentation rehearsal. Teacher displays the presentation structure slide: identify similar shapes; state the scale factor; show or describe a net; explain the composite solid; present surface-area reasoning; conclude with the answer and units. Students rehearse a 2–3 minute presentation with a partner, using cue cards or the sentence stems on the worksheet. Partners check that the explanation includes evidence rather than only a final answer.

6. 28–30 min · Share and exit check. Teacher uses the plenary and exit-question slide to invite one or two brief examples and collects the worksheet. Students complete the exit response: “The most important reason for excluding a shared face is ___,” and rate their readiness from 1 to 4 with one next step for the final presentation.

Resources

• the complete project review and presentation deck
• the exposed-face inventory and calculation sheet
• Student project models or construction materials
• Calculators
• Rulers and measuring tools
• Graph paper or plain paper
• Four-level project rubric
• Pencils, coloured pens, and sticky notes
• Optional cue cards or recording device

Assessment

• During Checkpoint 4, verify that students have identified all exposed faces, excluded shared internal faces, used appropriate formulas, and recorded square units.
• Confer with groups using the rubric; ask students to justify one calculation and explain how the scale factor appears in the model.
• Collect the worksheet and exit response to identify students needing calculation support or presentation coaching before Lesson 8.

Differentiation

• Provide a partially labelled model diagram, a formula bank, colour-coding for corresponding faces, and a worked example for students needing support.
• Offer sentence stems such as “This face is exposed because…,” “The shared face is excluded because…,” and “The scale factor shows…”.
• Allow cue cards, speech-to-text, a recorded presentation, or a partner presentation for students with communication, language, processing, or motor needs.
• Challenge ready students to verify the total using a second method, compare the surface area before and after joining solids, or explain how changing the scale factor would affect surface area.
• Pair multilingual learners with supportive peers and pre-teach terms including exposed face, shared face, net, composite solid, scale factor, and square units.