Learner Name:………………………………………………………………….
Grade 9
Natural Science
April 2014
SBA: Investigations
Marks: 20
Strand: Matter & Materials
SA: 1, 2 & 3
Time: 45 min.
Prepared by: L.A Ncongwane (Mrs)
Moderated by: C. Sampson (Ms)
Investigating rust
You will need:
 Three iron nails (same type and size).
 Three glass or plastic jars with lids (same type and size).
 Salt
 Water (600ml)
 Paintbrush
 Water-based paint
 Oil-based paint
Follow the instructions in the table and complete the observations column.
Method
Instructions
Jar 1
Pour 200ml water and 1
teaspoon salt in jar. Close
the lid.
Pour 200ml water and 1
teaspoon salt in jar. Paint
the nail with water-based
paint. Allow to dry, place it
in the jar and close the lid.
Pour 200ml water and 1
teaspoon salt in jar. Paint
the nail with oil-based paint.
Allow to dry, place it in the
jar and close the lid.
Jar 2
Jar 3
1.
2.
3.
4.
5.
6.
7.
8.
Observations after two
weeks
What is the aim for this investigation?
Formulate an investigative question for this experiment.
Formulate a hypothesis for this investigation.
Identify the following variables:
a) Independent
b) Dependent
c) Constant (identify four)
What can you say about the results from the table above (experiment results)?
Do the results match your hypothesis? Explain.
Write a definition for rust.
Name the conditions needed for rust to take place.
TOTAL: 20
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(2)
(2)
(1)
(1)
(4)
(2)
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(2)
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WORKSHEET
1. Aim:_________________________________________________________
_____________________________________________________________
___________________________________________________________(2)
2. Investigative Question:
_____________________________________________________________
_____________________________________________________________
_____________________________________________________
(2)
3. Hypothesis:
(2)
4. Independent Variable:
(1)
5. Dependent Variable:
(1)
6. Constant Variables:
(4)
7. Results:
(2)
8. Compare Results with hypothesis:
(2)
9. Definition of Rust:
(2)
10.Conditions for Rust to take place:
(2)
TOTAL
20
Grade 9
Natural Science
April 2014
SBA: Investigations
Marks: 20
Strand: Matter & Materials
SA: 1, 2 & 3
Time: 45 min.
Prepared by: L.A Ncongwane (Mrs)
Moderated by: C. Sampson (Ms)
MEMO
1. Aim:
To determine which paint preserve metal better/prevent rust better. 
(2)
2. Investigative question:
Does oil-based paint preserve metal better/prevent rust better than water-based paint? 
(2)
3. Hypothesis:
Oil-based paint preserve metal/prevent rust better than water-based paint.
(2)
4. Independent Variable:
Type of paint 
(1)
5. Dependent Variable:
Rust 
6. Constant Variables:
Amount of water (200ml) 
Salt (1 teaspoon) 
Same size jars 
Same type & size of nail 
(1)
(4)
7. Results:
There was some rust on the nail without paint, water-based paint was starting to peel off
the nail and there was no rust on the nail with oil-based paint. 
(2)
8. Comparison of results with the hypothesis:
The hypothesis proved to be true.  Oil-based paint preserve metal/prevent rust better
than water-based paint. 
(2)
9. Rust is:
A slow chemical reaction of iron with oxygen in the air and in the presence of water. 
OR a reddish brown material that develops on the surface of a metal.
(2)
10. Conditions for rust: (Reaction of iron with)
Oxygen/air and water. 
TOTAL :20
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