Prove it!
What is proof?
Sureness
•Certainty
•How sure can we be?
Kinds of proof
• Mathematical
• Scientific
Mathematical proof
• Prove that 7x3=21
• 3+3+3+3+3+3+3=21
• Proofs mean that you
can make rules, so 7x3
is always 21
Pythagorus theorum
• the square of the hypotenuse=squares of
other 2 sides
Pythagorus was right
His logic was worked out step by step.
It is completely correct because every
step leads on from the last.
Scientific proof is different.
The Chocolate Conjecture
• Eating chocolate before you
do sums will make you
brainer. You will be able to get
more sums right!
• PROVE IT.
Design a good tests to investigate
the chocolate conjecture
• This is scientific proof.
• We need to do a test to find
out.
• What would you do?
• How would you do it?
Sums sheet
• 1+3 =
• 2+1 =
• 1+1=
• 3+2=
• 2+2=
Good tests
• Comparisons
• Equal comparisons – control
groups
• Before and after
• Useful measurements
• Logical reasons for changes
• Placebo effects
why do we need fair tests?
• what happens when we don’t do good
tests?
• what could go wrong?
Why do we need fair tests?
how did we find out?
• science is about noticing things and
thinking about WHY
• scientists can test ideas and find out if
they are right or not
• this saves lives!
people used to think smoking
was good for you
how did we find out that
smoking harms us?
• science!
doctors who
smoked
doctors who
didn’t smoke
50 years
passed
scientists compared the two groups
people who smoked had more diseases and died younger
this showed smoking harmed us
• lots of other studies in different places
showed that smoking harmed us too
• we are very sure that smoking is bad for
us
scary statistics
• do you ever see scary statistics?
• would you like to help your mum and dad
when they read newspapers?
BROOMHILL NEWS – science week
2013
Broomhill School Science Week 2013
cut risk of ATTACK
by zombies by
50% !!!
ONLY £500!
• £500 to cut the risk of zombie attack by
50%
• that’s cutting the risk of attack in half!
• would you buy it?
but...
• cutting the risk in half with a zombie kit
sounds good
• but what was the risk to start with?
• what’s it half of?
• 100% RISK OF ZOMBIE ATTACK
• Means the Kit can cut the risk to 50%
But
• 1% risk of Zombie Attack
• HALF OF 1% means the kit reduces the
risk of attack to 0.5%
• DOESN’T SOUND AS GOOD!
• BUT zombies DON’T EXIST
• there is NO CHANCE OF A ZOMBIE
ATTACK
• The Zombie Kit cuts the risk by 50%
• BUT HALF OF NOTHING IS NOTHING
• SO THE KIT IS RUBBISH
STOP 90% OF ALL
PAPERCUTS!
GREAT NEW INVENTION!
ONLY £100!
BUT!
• ONLY 10 out of 1000 of children get a
papercut every year
• if we cut the risk of papercuts by 90%
• instead of 10 out of 1000 children with
papercuts
• it’s 1 in 1000
• but you have to wear gloves all the time!
things that sound good might
not be
• Science is about looking, thinking and
testing
• when we don’t do fair tests, we make
mistakes and harm people
• sometimes numbers can trick us - so we
have to be careful