Teacher's notes and answers to questions in the book - Hodder Plus ...

WJEC GCSE Additional Science Teacher’s Notes
2. Pick one of your hypotheses and suggest how you might test it.
Hypothesis 1 could be tested by flooding the room with strong-smelling air freshener to
‘mask’ the detection of the owner’s smell, and see if Prince still goes to the window (it
would be difficult to be certain if the masking works, however). Hypothesis 2 could be
tested by getting the owner to drive home in a different car, and see if Prince still goes to the
window. Hypothesis 3 is easy to test if the owner arrives home significantly earlier or later
than normal. If Prince still goes to the window just before his arrival in those circumstances,
it is clearly not related to the time.
_Drawing conclusions – is my hypothesis supported__
(pages 5–7)
Questions
3. Natalie had a hypothesis that wet paper could hold less weight than dry paper. She tested paper bags,
adding weight 10 g at a time until the bag broke. She tested 10 dry bags, and then soaked 10 similar
bags in water and tested them. In every single case, the wet bags broke with less weight in them than
the dry bags. What should Natalie’s conclusion be
The correct answer is b Her hypothesis is supported.
4. Glyn had a hypothesis that a certain brand of insulated mug did not actually keep drinks any warmer
than a normal ceramic mug. He timed how long it took water to cool by 10 °C in the two types of mug.
He ran the test 50 times. On average, the water took 6 minutes longer to cool down in the insulated
mug, and in all 50 tests the water in the ceramic mug cooled quicker. What should Glyn’s conclusion
be
The correct answer is d His hypothesis should be rejected.
TASK Can people tell the difference between butter and a
butter spread (page 7)
This is a difficult exercise. It has to be difficult because the aim is to test if pupils can draw
appropriate conclusions from ‘real’ science results, which are very often not completely ‘black
and white’. There would be little point giving pupils data that very clearly supported or
contradicted a hypothesis.
1. Patrick and Isobel’s hypothesis was ‘People cannot tell butter spread from butter’. The alternative is
‘People can tell butter spread from butter’. Comment on the evidence for each of these hypotheses.
‘People cannot tell butter spread from butter’ – Pure guesswork would lead to roughly 50%
success. Although there is a 56% success rate here, the difference from 50% is not big
enough to reject the hypothesis, but it is not supported by this evidence.
‘People can tell butter spread from butter’ – despite the 56% success rate, the difference is
not big enough to clearly support this hypothesis. In addition, the results are quite variable
from person to person. There is weak evidential support, but overall the results are
inconclusive.
2. What is your conclusion from these results
The results do not support Patrick and Isobel’s hypothesis, but the evidence is too weak to
reject it.
2