Grade 3 · Science · Unit 4 of 7
Strong & Stable
Strength, stability, struts and ties
What your child practises
Strength as holding a load and stability as staying balanced, how shape, a wide base and materials help, and how struts (pushed) and ties (pulled) work in a frame.
Saskatchewan Curriculum outcome: SM3.1, SM3.2 · materials, joins and what makes a structure strong and stable
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Which shape is very strong in frameworks, like the sides of a bridge?
🔺- oval
- triangle
- curve
- circle
Show answer
triangle
Hint: Triangles do not bend out of shape easily when pushed.
Question 2
Struts and ties together help a bridge because they…
🌉- change its colour
- make water flow under it
- share the load by being pushed and pulled
- make the bridge lighter than air
Show answer
share the load by being pushed and pulled
Hint: Some parts are squeezed and some are stretched, so the load is spread out.
Question 3
Plywood is made of thin layers of wood glued together. Why is it strong?
🪵- layers glued together add strength
- it is lighter than air
- it has no grain
- it is thinner than wood
Show answer
layers glued together add strength
Hint: Joining layers can make a material stronger than a single layer.
Question 4
What is the best way to keep a tall tower stable in strong wind?
🗼- a wide base fixed to the ground
- a narrow base
- no foundation
- heavy weights on top
Show answer
a wide base fixed to the ground
Hint: Stability comes from a wide, firm base.
Question 5
Which property is most important for the material in a boat's hull?
⛵- it is see-through
- it dissolves in water
- it keeps water out and floats
- it is very soft
Show answer
it keeps water out and floats
Hint: A boat has to stay afloat and not leak.
Question 6
A wooden post holds up a roof. The post is a…
🏠- strut
- cable
- tent
- tie
Show answer
strut
Hint: A strut is pushed on. It stops something from being squashed.