📦Unfold It Into a Net
🧊3D Shape
A 3D shape is made of flat faces, lines called edges, and corners called vertices.
📄Its Net (unfolded)
A net is the shape flattened out. A cube unfolds into 6 squares — find each area, then add them up!
✏️Worked Example
📐Surface area of a 4 × 3 × 2 box
1Top + bottom: 4 × 3 = 12, twice → 24
2Front + back: 4 × 2 = 8, twice → 16
3Left + right: 3 × 2 = 6, twice → 12
4Add the faces: 24 + 16 + 12
Surface Area = 52 square units ✅
⚖️Surface Area vs. Volume
🎁Surface Area
Covers the outside.
Add up every face's area.
Measured in square units (u²).
🧊Volume
Fills the inside.
Count the cubes inside.
Measured in cubic units (u³).
🔑Key Terms
🎁Surface Area The TOTAL area of all the outside faces of a 3D shape.
📄Net A flat 2D pattern that folds up into a 3D shape.
⬜Face One flat side of a 3D figure.
📏Edge Where two faces meet — a line segment.
📍Vertex A corner where edges meet (plural: vertices).
🔲Square Unit A 1×1 square — surface area is measured in these.
⭐
Remember: surface area covers the OUTSIDE — find the area of every face, then add them all together!