Learning Targets

Standards: CCSS 6.G.A.2 · 6.G.A.4 Time: ~45 min Materials: This activity (device or printed), scratch paper Grade 6
Teacher Notes (not printed)

Pacing

  • Launch (5 min): Read "The Brief" together. Anchor the scale: "1 grid square = 1 foot." Model reading length, width, and water depth off the tank blueprint.
  • Design work (30–35 min): Students complete Task 1 → 4 in order. Task 4 (the Build Sheet) uses results from Tasks 1–3, so encourage them to check each surface as they go.
  • Debrief (5–10 min): Discuss the fractional-edge volume, the net → surface-area connection, and the Level 2 water weight and glass-budget reasoning.

Differentiation

  • Level 1 (support): Use the green callouts and bilingual (EN/ES) prompts. Provide a printed formula card. Let students count unit cubes on the volume blueprint and click the net panels one at a time.
  • Level 2 (enrichment): Have students compute the water weight (62.4 lb per cubic foot) and solve the glass-budget inequality for the most expensive glass grade the build can afford.

STEM Connection

  • This is a true engineering design task: Define → Model → Calculate → Estimate → Decide. Students apply volume and surface-area math the way an aquarium engineer does — sizing tanks by volume, cutting glass panels from nets, and pricing a build against a hard budget and a structural water-weight limit.

Answer key

  • Q1.1 main-tank volume = 18 × 8 × 6 = 864 ft³
  • Q1.2 fractional ledge volume = 8 × 3 × 1½ = 8 × 3 × 1.5 = 36 ft³
  • Q2.1 triangle base area = ½ × 6 × 4 = 12 ft²
  • Q2.2 reef-wedge volume = 12 × 10 = 120 ft³
  • Q3.1 net panel count = 6; Q3.2 surface area = 2(18×8) + 2(18×6) + 2(8×6) = 288 + 216 + 96 = 600 ft²
  • Q4.1 pyramid skylight surface area = base 36 + 4 triangles 4×(½ × 6 × 5)=60 → 96 ft²
Unit 10 · Math Architect · Volume & Surface Area (6.G.A.2 · 6.G.A.4)

Design Challenge: The Coral Cove Aquarium

You are the lead exhibit engineer for Coral Cove Aquarium. The director wants a brand-new ocean exhibit built from glass prism tanks and a glass pyramid skylight. Use volume to size the water, use nets to size the glass, estimate the cost and the water weight, and bring the build in under $90,000 without overloading the floor.

Standard 6.G.A.2 Standard 6.G.A.4 Volume of Prisms Nets & Surface Area STEM Design Cycle
1 · DefineRead the brief & constraints (budget, weight, scale).
2 · ModelRead dimensions off each scale blueprint.
3 · CalculateFind volumes and surface areas.
4 · EstimateTurn volume & area into cost.
5 · DecideAdjust the plan to meet budget & weight.
Specs approved: 0 / 7

The Brief

The director handed you a scaled exhibit plan. Every blueprint on this page uses the same scale:

SCALE  1 grid square = 1 foot  ·  exhibit plan drawn to scale

Deliverable 1
Compute the volume of each tank from its scale drawing.
Deliverable 2
Use nets to find the glass surface area, then price it.
Deliverable 3
Keep the build under $90,000 and the water weight safe.
Level 1 · Support

Volume is how much space a solid fills, measured in cubic feet (ft³). Surface area is how much flat material covers the outside, measured in square feet (ft²). A net is the shape you get when you unfold a solid flat — every face becomes a piece you can measure.

Español: El volumen es cuánto espacio llena un sólido (pies cúbicos, ft³). El área de superficie es cuánto material cubre el exterior (pies cuadrados, ft²). Una red (net) es el sólido desdoblado en plano: cada cara es una pieza que puedes medir.

Engineer's Formula Toolkit

l × w × h
Rectangular prismV = l × w × h
(½ b h) × length
Triangular prismV = (½ b h) × L
add every face
Surface area (net)SA = Σ face areas

Strategy — for volume, fill the solid with unit cubes. For surface area, unfold the solid into a net, find each flat face, then add them all up. Same solid, two different questions.

Task 1 · The Main Reef Tank Rectangular prism · V = l × w × h

The centerpiece is a glass rectangular prism tank. Read its dimensions off the scale blueprint, then size the water it holds. Use the cube packer below to see how unit cubes fill the tank before you calculate. A low coral ledge runs along the back with a fractional height — size that too.

V = ?
Cube packer — live preview0 cubes
1
1
1
Layer (L × W)
1
Layers stacked
1
Volume
1 ft³

Build up to 18 × 8 × 6 one layer at a time. The volume equals the base layer (l × w) multiplied by the number of layers (h).

length = 18 ft h = 6 ft w = 8 ft Main Reef Tank
Isometric view · Glass tank1 square = 1 ft

Q1.1 — Volume of the main tank (18 ft × 8 ft × 6 ft)

ft³

Q1.2 — The coral ledge is a smaller prism: 8 ft long, 3 ft wide, and only 1½ ft high. Find its volume. (Hint: 1½ = 1.5)

ft³

Level 1 · Support

Volume of a box = length × width × height. Multiply two numbers first, then multiply by the third. For 1½, use 1.5.

Español: Volumen de una caja = largo × ancho × altura. Multiplica dos números y luego por el tercero. Para 1½ usa 1.5.
Level 2 · Enrichment

Saltwater weighs about 62.4 lb per cubic foot. If the main tank is filled, about how many pounds of water sit on the floor? (864 × 62.4). Why does an engineer need to know that number before building?

Task 2 · The Shark-View Wedge Triangular prism

A wedge-shaped viewing tunnel sits beside the reef. Its cross-section is a triangle, and it runs the full length of the wall — that makes it a triangular prism. Find the triangle base area first, then the volume.

base = 6 ft h = 4 ft length = 10 ft Wedge
Triangle base 6 × 4 · runs 10 ft1 square = 1 ft

Q2.1 — Area of the triangle cross-section (½ × 6 × 4)

ft²

Q2.2 — Volume of the wedge (base area × length, length = 10 ft)

ft³

Level 1 · Support

Two steps. (1) Find the triangle area: ½ × base × height. (2) Multiply that area by how long the prism is.

Español: Dos pasos. (1) Área del triángulo: ½ × base × altura. (2) Multiplica esa área por el largo del prisma.
Level 2 · Enrichment

A triangular prism holds half the water of the rectangular box that surrounds it (6 × 4 × 10 = 240 ft³). Does your answer match 240 ÷ 2? Explain why the triangle prism is exactly half.

Task 3 · Cutting the Glass (Unfold the Tank) Net · surface area

Before the glass shop can cut panels, you must unfold the main tank into a net — every face becomes a flat panel. Click each panel on the net to mark it "counted," then add the areas to get the total glass surface area.

Back 18×6 End 8×6 Bottom 18×8 End 8×6 Front 18×6 Top 18×8
Panels counted: 0 / 61 square = 1 ft

Q3.1 — How many panels (faces) does the tank net have? Click all of them on the diagram, then enter the count.

panels

Q3.2 — Total glass surface area. Add the six panels: two 18×8 + two 18×6 + two 8×6.

ft²

Counted area
0 ft²
Panels left
6
Level 1 · Support

A box has 3 pairs of matching faces: top & bottom, front & back, two ends. Find one of each, then double it, then add.

Español: Una caja tiene 3 pares de caras iguales: arriba y abajo, frente y atrás, dos extremos. Halla una de cada par, duplícala y suma todo.
Level 2 · Enrichment

The real tank has no glass top (it is open for feeding). What surface area of glass do you actually order if you skip the top 18×8 panel? (600 − 144).

Task 4 · The Pyramid Skylight & Build Sheet Pyramid net · budget

A glass square pyramid skylight crowns the exhibit. Its net is one square base plus four triangles. Find its surface area, choose a glass grade, then complete the Build Sheet under the $90,000 budget.

Base 6×6 slant 5 slant 5 5 5 base 6 ft
Square pyramid net · 1 base + 4 triangles1 square = 1 ft

Q4.1 — Surface area of the pyramid skylight. Square base (6×6) plus four triangles (each ½ × 6 × 5).

ft²

Choose a glass grade (for the 600 ft² tank)

Selected
Tank glass
600 ft²
Glass cost
$0

Live glass cost = 600 ft² × price/ft². This feeds straight into your Build Sheet below.

Final Build Sheet

Item Quantity Your cost ($)
Tank glass — your grade 600 ft²
Pyramid skylight — low-iron @ $55/ft² 96 ft²
Saltwater fill — 864 + 120 ft³ @ $3/ft³ 984 ft³
Pumps, frame & labor — fixed
Total estimate $0

Pyramid cost = 96 ft² × $55. Water cost = 984 ft³ × $3. Compute each and enter it to confirm you can turn area and volume into money.

Budget
$90,000
Remaining

Level 2 · Enrichment

If the acrylic grade ($70/ft²) pushes you over budget, what is the most expensive tank-glass price p you can still afford? Set up and solve the inequality:

600·p + 5280 + 2952 + 38000 ≤ 90000

Level 1 · Support

Total = tank glass + pyramid + water + fixed. Remaining = budget − total. Positive remaining = under budget (good). Negative = pick a cheaper glass grade.

Español: Total = vidrio del tanque + pirámide + agua + fijo. Restante = presupuesto − total. Si es positivo, estás dentro del presupuesto.

Engineer's Sign-off

When every spec checks out and your plan is under budget, submit it to the aquarium director. Enter your name in the field below, then press Submit plan & grade to save your score as a PDF or DOC.

Performance Rubric — Volume & Surface Area Design Challenge (6.G.A.2 · 6.G.A.4)

Level Score Descriptor
4 — Exceeds 7 / 7 Reads every scale blueprint accurately. Finds prism volumes (including a fractional edge) and triangular-prism volume correctly, uses nets to find surface area of a prism and a pyramid, and brings the build under budget. Can explain water weight and the glass-budget inequality.
3 — Meets 6 / 7 Correctly computes most volumes and surface areas with at most one arithmetic slip. Completes the Build Sheet and reaches a valid under-budget plan.
2 — Approaching 4–5 / 7 Computes simple volumes but struggles with the fractional edge, the triangular prism, or the net surface area (e.g., forgets to double matching faces or to halve the triangle). Partial cost/budget work.
1 — Beginning 0–3 / 7 Few correct answers. Confuses volume with surface area, or misreads the scale. Needs reteaching on prism volume and on building surface area from a net.