Can you trick your friends with this straw that
doesn’t work? It’s part magic, part science
and lots about air pressure.
What you will need:
•2 drinking straws
•A glass of drinking water
What you will do:
1 Put a straw in your glass and have a drink of
water. What exactly do you do to make the water
come up the straw?
2 Now place the other straw on the table and use
the pin to punch some holes in the top third of
the straw. If there is a pattern on the straw you
could use it to hide the holes.
3 Now use the straw with the holes to take a drink
of water. How did you go?
What is going on?
When we drink using a straw we suck on the end of
the straw while the other end of the straw is in
the drink. When we first suck on the straw we
suck the air out which means we reduce the air
pressure inside the straw. The air pressure
outside the straw is then higher so it pushes
down on the drink in the cup and forces some of
the liquid up the straw. This process keeps
going until the drink has reached our mouth, but
it is so fast we don’t even think about it!
• Can you explain what the holes in the straw
• Try using the straw with the holes in it
upsided down – with the holes in the drink.
What happens? Keep drinking and see if
• What happens when you blow in the straw?
Explaining using what you now know about air
• Could you trick someone with a holey straw?
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