Solid Figures, Surface Area, and Volume
Recognize 3D shapes, count faces, edges, and vertices, and solve surface-area and volume problems without mixing them up.
Solid Figures, Surface Area, and Volume
Not yet started on this browser.
Surface area is outside. Volume is inside.
Volume = space inside a solid.
Rectangular prism: 6 rectangular faces, 12 edges, 8 vertices.
See the solid first, then the net
First look at a simple 3D drawing with only the outside edges. Then look at the net. If the solid feels hard to picture, the net makes the faces easier to count and is often easier for surface area.
Six patterns you should recognize
1. Count parts of a cube
A cube has 6 faces, 12 edges, and 8 vertices.
2. Rectangular prism volume
L=8 cm, W=5 cm, H=3 cm.
8 × 5 × 3 = 120 cm³3. Cube surface area
Side length = 4 cm.
6 × 4² = 6 × 16 = 96 cm²4. Rectangular prism surface area
L=6, W=4, H=2.
2(24 + 12 + 8) = 885. Triangular prism volume
Triangular base: b=6 cm, h=4 cm. Prism length=10 cm.
(1/2 × 6 × 4) × 10 = 120 cm³6. Square pyramid volume
Square base side=6 cm, height=9 cm.
1/3 × 36 × 9 = 108 cm³Outside or inside?
A gift box is 10 cm long, 6 cm wide, and 4 cm high. How much space is inside the box?
- Space inside means volume.
- Use L × W × H.
- 10 × 6 × 4 = 240.
Watch out for these
Volume uses cubic units, such as cm³.
Surface area uses square units, such as cm².
Count each edge once, even if it is dashed or hidden.
A pyramid with the same base and height as a prism has one third the volume.
Build the skill
Can you tell the solid fact fast?
Can you do it without hints?
Score 5/5 to verify this competency.
Still mixing up surface area and volume?
Send Teacher Abi the item that confused you. I can help you identify whether the problem is asking about the outside or the inside.
Message Teacher AbiChoose your next step
Next competency: Measurement and Unit Conversion
No comments:
Post a Comment