Touch the Past
M useum s Education Service
Iceberg!
Key Stages: 2 & 3
National Curriculum Links: Sc1 1a,b, 2a,b,c,d,e,f,g, Sc3 1a,e 2a,d, Sc4 2b,d,
Ma2, Ma3, Ma4
Main Subject Focus: Science
Overview:
The Titanic was sunk when it hit an iceberg. Why do ice and icebergs float?
Does the water being salty make any difference to the amount of iceberg above
the water? Students will learn about the concepts of mass, volume and density .
Learning Outcomes:
Children will understand the following:
•
Objects that are less dense than water can float
•
Water expands when it freezes and has a lower density than water
•
Air helps dense materials to float
•
Salinity (amount of salt) of water affects the buoyancy (floatability) of ice
when the water is frozen .
•
The greater the salinity of an iceberg, the smaller the percentage of the
iceberg that will remain beneath the surface of the water.
•
The size of an iceberg has no affect on the percentage of the iceberg
remaining beneath the surface of the water.
Materials:
Clear box
Weighing scales
Plastic cup 'icebergs'
Water
Ruler
(1 large with salt & 1
Plastic Bottles
Worksheets & pencils
without, 1 small with
salt and 1 without)
Activity Structure
1. Read out the definitions from the Pupil's Information sheet before you begin.
2. Show the students the 2 bottles -one of water and one of ice. Ask which has
the greater volume -the water or the ice. The answer should be ice as the
frozen water takes up more space.
3. Ask them to weigh the bottles. They should both weigh the same. Both
bottles still have the same mass, as they started with the same amount of
water.
4.
5.
6.
7.
8.
9.
Now ask the students which bottle has the greater density and why. The answer should be that the water has greater density, because as ice freezes it
expands and becomes less dense. Demonstrate this by asking the students
to place both bottles in the water and measuring which bottle is deeper into
the water.
Explain to the group that they are now going to conduct an experiment to
demonstrate the affect of salinity, or amount of salt, on floating icebergs.
Their experiments will answer two questions: Does the presence of salt in an
iceberg make the iceberg more or less buoyant (floatable)? and Does the
size of an iceberg affect its buoyancy (floatability)?
Show the group the 4 plastic cup 'icebergs'. Ask them to predict which icebergs will be least buoyant (i.e. which will sink most in the water). Their predictions should be recorded on the worksheet.
The students should then test their predictions by placing the 'icebergs' in
the water and measuring the height of each cup above the water. The results should be recorded on the worksheet.
Have students measure the height of each iceberg with a ruler; then have
them separately measure the part of each that is above and below the surface of the water. Next have students calculate the percentage of each iceberg that is below the surface of the water. They should record their findings
on the worksheet.
Have groups discuss their findings and determine whether the findings confirm their predictions. Students should conclude that because the percentages are the same for the large and small icebergs that are both fresh and
the same for the large and small icebergs that are both salt, size has no affect on the buoyancy of an iceberg. Because the percentages for both the
large and small saltwater icebergs are lower than those for the freshwater
ones, students should conclude that the higher the salinity, the more buoyant
an iceberg will be.