Second Level Science
SCN 2-15a: By contributing to investigations into familiar changes in substances , I can describe how their characteristics have changed.
MTH 2-21a / 3-21a: I can display data in a clear way using a suitable scale, by choosing appropriately from an extended range of tables, charts, diagrams and
graphs, making effective use of technology
LIT 2-28a: I can convey information, describe events, explain processes or combine ideas in different ways
Significant Aspect of Learning
Knowledge and understanding of scientific ideas,
principles and concepts related to materials.
Learning Statements
•
Substances can change and such changes can
alter their characteristics.
•
Apply understanding of scientific concepts to
solve problems and provide solutions.
•
Develop informed views about the wider world,
in relation to scientific and environmental
issues.
Learning Intention
We are learning that substances can change and when
they do their properties can also change.
Success Criteria
In order to demonstrate a secure knowledge of
changing substances, pupils should be able to:
•
Identify that physical properties of reactants can be
different to the products following a reaction (e.g.
state, appearance).
•
Identify that some chemical properties of reactants
are different compared to products following a
reaction (i.e. their reactions or reactivity).
•
Identify which properties of a substance have
changed upon altering a substance chemically or
physically.
Context of Learning
Using their knowledge of changing substances and their properties, learners carried out a series of experiments
and research tasks relating to rusting. From this they were able to draw valid conclusions and make basic
predictions based on their findings. Activities included:
•
Identifying the properties of iron and rust (iron oxide)
•
Testing iron and rust for their magnetic properties
•
Researching how rust affects buildings and bridges and the impact this has on society
•
Investigate the composition and properties of some alloys
•
Compiling a graph from data and making predictions
Figure 1: What Causes Rusting?
Working with secondary
practitioners, as part of a
transition project, the
learners investigated the
rusting of iron. They were
introduced to rust
indicator (ferroxyl
indicator) and were
shown how the solution
changes colour if rust
(iron oxide) is present.
They were able to plan an
experiment which would
allow them to investigate
what was needed for iron
to rust.
The learner has observed three iron nails over a period of time. They have used an
investigative approach to test the role of air and water in rusting. The learner has
observed that rusting only occurred in the test tube where air and water were present.
Using the additional knowledge that rust has the chemical name: ‘iron oxide’ the
learner has hypothesised that it is oxygen from air that is used as a reactant.
Figure 2: What is Rusting/Rusting Word Equation?
Using their knowledge from the previous experiment, the learner has been able to represent
the material changing in a word equation, identifying that oxygen and water are reactants in
this process. Reactants and products are shown on the correct sides of the arrow. The learner
has also represented each substance using diagrams to indicate their physical appearance and
state.
Going further:
The learner has identified that oxygen is the relevant gas in air that has taken part in the
reaction. They have also referred to rust by its chemical name: iron oxide.
Figure 3: Experiments on Properties of Iron
and Iron Oxide
This learner has used their knowledge of the
element iron to devise an experiment into
the magnetic properties of iron and iron
oxide. From this they have concluded that
iron within a compound does not exhibit
magnetic properties.
Figure 4: Summary Table
The learner has then summarised and
compared the properties of iron and iron
oxide in the table.
Figure 5: Rusting in Society
This learner has researched instances of corrosion of iron/steel to identify the negative impact of
rusting in society. This extract describes a steel bridge collapsing due to corrosion and suggests a
way of protecting the iron/steel from corroding.
Learner conversation:
‘ What impact on society do you think rusting has?’
‘ I think it must cost a lot of money to repair bridges that have been affected by rust or to keep
them painted. If you paint them, like the Forth Road Bridge then water and air can’t get to the
iron so it shouldn’t rust.’
Learners were challenged to investigate an area of their choice related to changing the properties of metals. This learner has chosen to
investigate alloys.
Figure 6: Alloys and Changing the Strength of Steel
This learner has focused on steel. They have stated in their
introduction that carbon is added to iron to make it
stronger, supporting this statement with data presented as
a table, using suitable headings. Learners would reasonably
be allowed access to ICT to convert this data to a line graph,
however this learner has opted to present the graph by
hand, using an accurate scale and plotting the points
correctly. They have also labelled both axis. Other learners
may need support to draw the graph and could given a
graph in which the scale had been drawn and the axis
labelled. The learner was asked to justify why they have
converted their data to a line graph. Their response was
‘[the line graph] shows the results better. You can see if [the
trend] goes up or down just by looking at the line’. When
questioned further, they have correctly described the trend
and been able to predict the strength of steel with a higher
carbon content.
”If I needed a bridge that could withstand 250M Pa – what
percentage of carbon would the alloy need to contain?”.
The learner was able to use the graph to obtain the correct
answer – “0.44%”. He was able to go further when asked
“What can you tell me about the strength of the steel as the
percentage of carbon increases?”
Next Steps for the Learner
The pupil could also be given a graph showing the strength of steel ‘levelling off’ even if carbon is
added and draw a conclusion based on these results.
A third graph showing the ‘hardness’ of steel increasing as carbon is added could be presented to
the pupil. They could be asked to identify some advantages/disadvantages of increasing the
hardness of steel and using both graphs choose their ‘ideal’ percentage of carbon, with a
justification relating to the properties.
Pupil Voice
‘I have learned that when things react their properties can change, it may not be magnetic
anymore or it may change colour.’
‘I have learned that materials can be changed for good reasons , to make them stronger or more
shiny but sometimes when they change it’s not a good thing , like rusting.’
‘If a substance has reacted, I want to learn how I could get the original substance back’