Small plastic fish tanks round glass fish bowl, golf ball, polystyrene ball all identical sizes.

ACTIVITY

Feel weight of each ball.  Drop each ball individually into tank.

CONCEPT/LANGUAGE

Which ball is heaviest, lightest?  Which ball sinks, floats?

Two plastic guttering pipes, balls of different materials, preferably the same size e.g. plastic, hollow, solid.. wood, wool, rubber, polystyrene.

ACTIVITY

Place the two pieces of guttering into the water trough at different angles so that each slope of the pipe is different.
Let each ball roll down the pipe first down the highest incline, then down the lowest.

CONCEPT/LANGUAGE

Weight - heavy light balls.  Which ball goes the fastest - slowest? 
Which ball makes the biggest splash?  Does it sink?
Which makes the smallest splash?  Does it float?  If the guttering pipe is higher, does the ball go quicker?

Plastic boats of different sizes (Arnolds & Tupperware)
Marbles. 

ACTIVITY

Put boats into water.  Put marbles onto the boats until they sink.  Launch the boats down the guttering as in the previous activity.

CONCEPT/LANGUAGE

How many marbles to sink the boats?  What happens to the marbles?  Does the largest boat need more marbles to sink it?
Which boat makes the biggest splash?

Natural materials that sink and float.  Chalk, clay in different shapes, pumice stone, sponge, shell, coral, pine cones, acorns, leaves, sand, leather, fur wood.  3 plastic washing up bowls in red, blue, green.

ACTIVITY

Place objects one at a time in water.  Watch how each object behaves in water.
If it sinks put in red bowl.
If it floats put in blue bowl.
If it floats and sinks or not sure put in green bowl.

CONCEPT/LANGUAGE

Do they sink or float or do they absorb water?  Do they float first then take in water and sink?  How do they feel when they are in the water?  Do they look different?  Do they smell differently?
When they sink, do they take a long time?

Objects that float - balloon, acorn, cord, cork, cotton reel, egg shells, ice, metal  basin, plastic cup, plastic soap dish, hollow rubber ball, squeezy bottles, writing paper.  All in blue bowl.  In red bowl have soap, nails, tiny stones, paper clips, clay, chain, key, pencil.

ACTIVITY

Place objects in blue bowl into water.  All will float.  Have bowl of objects that sink at one side in red bowl.

CONCEPT/LANGUAGE

Do all these things float?  What can we put with them to make them sink?  Acorn-clay;  cotton reel - lead pencil;  soap dish - soap;  cork - nails into it;  egg shells - small stones;  balloon - put water in it;  cord - add key;  metal basin - gradually pour water into it;  writing paper - paper clips.

Objects that sink in red bowl - metal washers, magnets, scissors, stone, metal spoon, metal weight, badge, coin, key,
screws, nails different lengths. (This can be done in a plastic fish tank which smaller children can see more easily).

ACTIVITY

Feel all the different objects  Place them in the water - watch how they sink.

CONCEPT/LANGUAGE

What are most of the sinking objects made of?  Do they sink quickly to the bottom of the tank?  Do they sink?  Is anything else happening?

ADDITIONAL RESOURCES

Magnets can be added as an activity especially with the metal objects sinking.  Weebles can be put into the fish tank and a swimming pool set up with the slides.  If some of the weebles have a hole in them they become full of water and sink-the others float to the top.