Beth yw priodweddau siapiau 3D?

Ffocws dysgu

Dysga adnabod a defnyddio siapiau 2D a 3D.

Mae'r wers hon yn cynnwys:

• un fideo
• dau weithgaredd

Lesson content

Learn to recognise and use 2D and 3D shapes.

This lesson includes:

• one video
• two activities

Fideo / Video

Dysga am nodweddion siapiau 3D gan gynnwys ochrau a fertigau.

Learn about the properties of 3D shapes, including edges and vertices.

Nodiadau i rieni

• Mae gan giwb 3D 6 wyneb, 12 ochr/ymyl ac 8 cornel/fertig (dyma le mae’r ochrau yn cwrdd)
• Mae gan y pyramid sylfaen sgwâr 5 wyneb, 8 ochr/ymyl a 5 cornel/fertig
• Mae gan y sffêr 1 wyneb - does dim ochrau na fertigau gan y sffêr

Notes for parents

• A 3D cube has 6 faces, 12 edges and 8 corners/vertices (this is where the edges meet)
• The square-faced pyramid has 5 faces, 8 edges and 5 corners/vertices
• The sphere has 1 face - it does not have any edges or vertices

Priodweddau siapiau 3D

Mae gan siapiau 3D wynebau (ochrau), ymylon a fertigau (corneli).

Wynebau

Arwyneb gwastad neu grwm ar siâp 3D yw wyneb. Er enghraifft, mae gan giwb 6 wyneb, mae gan silindr 3 wyneb, a dim ond 1 sydd gan sffêr.

Ymylon

Ymyl yw’r lle mae 2 wyneb yn cyfarfod. Er enghraifft, mae gan giwb 12 ymyl, mae 2 ymyl gan silindr a does dim gan sffêr.

Fertigau

Cornel lle mae ymylon yn cwrdd yw fertig. Er enghraifft, mae gan giwb 8 fertig, mae gan gôn 1 fertig a does dim gan sffêr.

Properties of 3D shapes

3D shapes have faces (sides), edges and vertices (corners).

Faces

A face is a flat or curved surface on a 3D shape. For example a cube has 6 faces, a cylinder has 3 and a sphere has just 1.

Edges

An edge is where 2 faces meet. For example a cube has 12 edges, a cylinder has 2 and a sphere has none.

Vertices

A vertex is a corner where edges meet. The plural is vertices. For example a cube has 8 vertices, a cone has 1 vertex and a sphere has none.

Gweithgaredd 1 / Activity 1

Dewisa’r siâp sy’n ateb y disgrifiad yn y brawddegau isod:
ciwb - côn - sffêr - pyramid gwaelod sgwâr

Select the shape that fits the description in the sentences below:
ciwb (cube) - côn (cone) - sffêr (sphere) - pyramid gwaelod sgwâr (square-bottomed pyramid)

Gweithgaredd 2 / Activity 2

Cydwedda'r siapiau â'u priodweddau 3D isod.

Match the shapes to their 3D properties below.