Problem Set 51 – Views of 3-D Objects and NetsClass 5 Maths · Chapter 13 Three Dimensional Objects and Nets · Problem Set 51 – Maharashtra Board

Summary: Problem Set 51 – Views of 3-D Objects and Nets

Three dimensional (3-D) objects have length, breadth and height — a box, a bottle, a table. Two dimensional (2-D) figures are flat, with only length and breadth — a drawing, a sheet of paper, a shadow.

A 3-D object looks different from the front, from a side and from above. A cylinder-shaped bottle looks like a rectangle from the front and a circle from above.

Maps show hills from above using curved lines; each line joins places at the same height, such as 200 m or 400 m.

A net is a flat shape that folds into a 3-D object. A cube's net has 6 equal squares; a cuboid's net has 6 rectangles.

Five equal squares joined edge to edge make a pentomino. Some pentominoes fold into an open box (a cube with no lid).

Key points to remember

• 3-D: length, breadth and height
• 2-D: only length and breadth (flat)
• Views: front, side, from above (top)
• Bottle: front = rectangle, top = circle
• Cube: 6 square faces, 12 edges, 8 corners
• Cuboid: 6 rectangular faces
• Net = flat shape that folds into a solid
• Pentomino = 5 joined squares → can make an open box

Problem Set 51 – Views of 3-D Objects and Nets – Notes

1. 2-D and 3-D

• Objects we can hold — books, glasses, tables, boxes — have length, breadth and height. They are three dimensional.
• A picture of an object on paper is flat. It is two dimensional, even when it is drawn so that it seems to have depth.
• Very thin things like paper sheets and shadows are treated as 2-D.

2. Front, side and top views

• Looking straight at the front of a cupboard you see a tall rectangle; from above you see a thin rectangle (its top).
• A tin or a water bottle shaped like a cylinder: front and side look like rectangles, the top looks like a circle.
• A cube looks like a square from every side.

3. Hills on a map

• From far away we can see how tall a hill is, but not how much land it covers.
• From a helicopter we see the land it covers, but not its height.
• So maps use closed curved lines marked 200 m, 400 m, 600 m… Each line joins points at that height. Lines close together mean a steep slope.

4. Nets of a cube and a cuboid

• If you cut open a box along some edges and lay it flat, you get its net.
• A cube's net has 6 equal squares, for example a row of 4 squares with one square above and one below the second square.
• A cuboid's net has 6 rectangles in three matching pairs.
• In a cube net, two squares with exactly one square between them in a straight row become opposite faces.

5. Pentominoes and dice

• A pentomino is 5 equal squares, each joined to another along a full side.
• Folding some pentominoes gives an open box (a cube without its lid). Five squares in one straight line cannot do it — the ends overlap.
• On a usual dice, opposite faces add up to 7: 1 and 6, 2 and 5, 3 and 4. Use the net to see which faces are opposite.

Formulas at a glance

Key terms

Problem Set 51 – Views of 3-D Objects and Nets – Flashcards

Read the question, answer it in your head, then tap the card to check. 10 cards.

Problem Set 51 – Views of 3-D Objects and Nets – MCQ Quiz

10 questions. Tap an option — you will see at once if it is right and why.

How to study Problem Set 51 – Views of 3-D Objects and Nets

⏱ About 30 minutes

1. Look (10 min)
   Pick a bottle, a box and a chair. Look at each from the front, a side and above, and sketch what you see.
2. Fold (15 min)
   Draw a cube net and a pentomino on card, cut them out and fold them.
3. Practise (5 min)
   Do the 4 'Try it yourself' questions, take the quiz and play 🎮 Play.