Ocean Currents

Ocean Currents



Materials

• 2 Jam Jars (Same Size)
• Squares of card/plastic
• Table salt
• Food Colouring
• Paper Towels
• Plastic/Baking Tray

Methods

1. Fill one jar with colourless fresh water (from the tap is fine) and the other jars with coloured salty water (tap water with salt added can be used).  Place both the jars in the tray. 
2. Place a piece of card on top of the salty water and invert the card (turn it upside down), the upward pressure of air will hold the card in place (most of the time).
3. Place the saltwater jar on top of the freshwater jar and have someone remove the card.  Do this over the tray in case of spillages.  Observe results.
4. Repeat No 1 - this time put  the freshwater on top of the salt water, remove card and observe the results.
5. Repeat No 1 - this time put the fresh water on top of the salt water and turn the jars horizontally (sideways).  Remove the card and observe.

What Happens

When the saltwater was placed on top, the water in the two jars mixed togheter.  This is because saltwater is heavier that freshwater and sunk down through the freshwater in the bottom jar.  When the freshwater is place on top is floats on top of the saltwater at the bottom.