EPISODE 3: CHANGING THE LIGHTBULB
LEVERS
TO TEACHERS AND PARENTS
A large focus in teaching science is around encouraging both curiosity
and the skills and dispositions to be able to find out or test things for
yourself. This includes developing an understanding about how science
itself works. The New Zealand Curriculum calls this the Nature of Science.
Tips about how to encourage these aspects are given in a
Use these to get your children talking, discussing, testing and thinking
about the science involved in Jiwi’s Machines. Have fun! The science
content involved in Jiwi’s Machines relates to the Physical World
Achievement Aims of the New Zealand Curriculum.
THE LEVER
The Lever – a rigid bar used to gain force, gain speed or change direction.
The Lever is a type of simple machine that moves about a fulcrum or pivot point,
usually to help lift heavy loads much more easily (with less effort). Originally
mentioned in EPISODE 1: CRUMBS, in this episode we extend our knowledge of
levers. The SCIENCE CLIP shows us that the ease of lifting a heavy load is affected
by where the fulcrum is.
Load = the object you are lifting
Fulcrum = point where the lever pivots
Effort = the force needed to make the object move
Establish that just as we’ve seen in Jiwi’s clips, a lever is very much like the seesaw
in a playground. What happens when you are at the playground on the seesaw
with an adult? Can you get them up in the air? Why not? What could you do to try
to lift their heavier load?
INVESTIGATION:
What happens to the effort needed if the
fulcrum changes position when lifting a
load? (This is the same thing as making the
length of the lifting arm longer or shorter)
BIG SCIENCE IDEA 1: Levers can make it
easier to lift a load.
BIG SCIENCE IDEA 2: The position of the
fulcrum can make it easier or harder to lift
a load.
INDOORS OPTION: Have children use their
30cm rulers, a pencil or pen, tape, two
paper cups, one larger weight and a range
of objects of the same weight (eg: marbles,
nuts or washers, Lego blocks, coins) to
construct their own lever. The paper cups
are taped or blu-tacked onto the ruler and
the pen is taped to the table.
How many small marbles (or other
weights) are needed in the Effort cup in
order to lift two large marbles (or other
weights) in the Load cup?
With the 15cm mark of the ruler positioned
across the fulcrum (pen), add a weight to
the Load cup. Now, one at a time, count
how many small marbles you need to add
to lift the Load. It is unlikely to balance
perfectly. You will be able to say though
that it takes between x and y little marbles
to lift the Load. Record this. Empty the
small marbles.
Now shift the ruler so that the fulcrum
is 10cm from the Effort cup. Again, how
many small marbles are needed to lift the
same Load? Record and empty the small
marbles.Shift the ruler one last time so that
the fulcrum is 10cm from the Load cup.
How many small marbles are needed to lift
the same Load?
OBSERVATIONS
What did you observe?
Is it measurable?
What might this mean?
RESULTS
WE USED ……………. AS OUR LOAD WEIGHT
WE USED ……………. AS OUR EFFORT WEIGHTS
Position of fulcrum
It took between _ & _ weights to lift the Load
15 cm (middle)
10 cm from Effort cup
10 cm from Load cup
Can the children relate what they have done in this investigation with what they
saw in Jiwi’s LEVER CLIP?
Can you now explain what happens to the effort needed if the fulcrum changes
position when lifting a load?
USE EVIDENCE
Students should be encouraged to ask
and answer questions such as:
How do you know that?
What makes you think so?
How could you check that?
So an example of this would be...
Can you think of an example
when this wouldn’t work?
OUTDOORS OPTION: The same
investigation can be carried out in a BIG
way outside if you have a scaffolding plank
and a strong fulcrum. Big is always fun.
Mind out for fingers and toes.
Make your own lever outside with the
fulcrum in the middle. Put two children
(Load) standing at one end. How many
children (Effort) are needed to lift the Load
into the air?
Now shift the fulcrum further away from
the Load, approximately halfway between
the middle and the Effort end. How many
children are needed to lift the Load into
the air? Ask the children if the same
children should be used? Why?
Lastly, shift the fulcrum towards the Load,
approximately half way between the
middle and the Load. How many children
are needed to lift the Load into the air?
JIWI WONDERS
• What other questions do you have
about how levers work?
• If you had a long scaffolding or
strong plank and a fulcrum, could
one child lift the Principal/ Teacher
/ Parent off the ground? How? Try!
• Where are levers used in everyday
life?
TYPES OF LEVERS
Depending on the position of load, fulcrum and effort, levers can be classified into 3 types.
1st Class Lever: The fulcrum is between the effort and the load eg: see–saw
2nd Class Lever: The load is between the fulcrum and the effort eg: wheelbarrow
3rd Class Lever: The effort is between the fulcrum and the load eg: tongs
ACTIVITY:
SORT THE LEVERS!
Collect a range of different types of lever
and have the children sort them into 1st,
2nd and 3rd class levers by trying them
out.
The sorts of things you could collect are:
1st: scissors, pliers, crowbar, hedge trimmer
2nd: nut cracker, wheel barrow, sack
barrow, bottle opener
3rd: fishing rod, broom, tongs, tweezers,
picture of a forearm lifting an object,
stapler
EXTENSION:
In EPISODE 1: TOAST BITE, the idea of
Mechanical Advantage was explained. It
means how much the machine multiplies
the force you put into it. It is relatively easy
to calculate the mechanical advantage
provided by levers by using the following:
MA = length from fulcrum to Effort divided
by length from fulcrum to Load
So if dE is 7cm and dL is 14 cm then
MA = dE / dL
= 7 / 14
= 0.5 or 1/2
- which means it is hard work to lift that load.
It would be easier to lift by hand.
If the fulcrum was moved to the other end however and the distances were as follows:
dE is 14cm and dL is 2 cm then
MA = dE / dL
= 14 / 7
= 2 - which means it is twice as easy to lift that load than it
would be if the fulcrum was in the middle!
Some ideas on how your body acts like a lever can be found at:
http://sciencelearn.org.nz/Contexts/Sporting-Edge/Looking-closer/What-levers-does-your-bodyuse
MATERIALS
Investigation – Inside option
Rulers
Pen / Pencil
Sellotape
Paper cups
One larger weight
Range of objects of the same
weight
Investigation – Outside option
Scaffolding plank
Fulcrum
Volunteers
Activity: Sort the Levers
Scissors, pliers, crowbar, hedge
trimmer, nut cracker, wheel
barrow, sack barrow, bottle
opener, fishing rod, broom,
tongs, tweezers, picture of a
forearm lifting an object, stapler
+ anything else you can think of.
NZ CURRICULUM PLANNING SUMMARY
Contextual Achievement Objective:
PHYSICAL WORLD; Explore and investigate
physical phenomena in everyday situations.
Nature of Science Achievement Objective:
INVESTIGATING IN SCIENCE; Any student
investigation may involve a variety of skills
(pattern seeking).
Big Science Idea: Levers can make it easier to
lift a weight.
Big Nature of Science Idea:
Scientists look for patterns in their
investigations.
The position of the fulcrum can make it easier or
harder to lift a load.
Weblinks: http://scienceonline.tki.org.nz/Nature-
of-science/What-is-the-Nature-of-Science/Teachersuggestions-Investigating-in-science
http://scienceonline.tki.org.nz/Introducing-fivescience-capabilities/Gather-interpret-data
http://scienceonline.tki.org.nz/Introducing-fivescience-capabilities/Use-evidence
Capability focus:
GATHER AND INTERPRET DATA; Are our
explanations robust (based on evidence from
our observations)?
USE EVIDENCE; In science, explanations need to
be supported by evidence.