Different Ways with the Water Cycle

Our river study naturally leads to learning about the water cycle.

A 50p charity shop find of a strategy game based on river tides.

It is truly amazing to discover the interconnectness of various seemingly random topics, but somehow we have been able to stretch our themed study of The Wind in the Willows further and further.  The rest of the series can be found here.

Desk Learning
We started off by printing off the water cycle exercise from here.   First, Tiger matched the labels to their definitions, followed by labeling the diagramme.

Since we had not covered water cycle formally before, I wanted to use the exercise above to gauge how much Tiger knew or didn't know, so that we could focus our efforts on learning new things rather than unnecessary repetition.  When Tiger needed a bit of clarification on the processes, we watched the clips here and here.

Finally, we worked through the section here for review and to test our understanding of this topic.


Hands-on Experiments
Enough of table-learning!  Time to get some hands-on work done so we did a few experiments related to our topic.

1) The classic experiment

Procedure:

1. Bring a pan of water to boil.  Observe the air bubbles in the pan and the steam (photo 1).
2. Put a few ice cubes in a foil tray and hold it above the steam - be careful not to get burned by the hot steam! (photo 2)
3. photo 3: Observe the moisture that forms at the bottom of the foil as the warm air meets the cold foil surface. (photo 3)
4. As more steam/vapour gathers on the bottom of the foil, the water molecules gather to form bigger drops which eventually fall. (photo 4)

2) Water cycle in a bottle

Procedure:

1. Cut the neck of the bottle and screw the cap on tightly.  Pour a cup of warm water into the bottle and place the top of the bottle as shown.  Use cellotape to seal the space where the two parts of the bottle meet.  Place the bottle under direct sunlight for 5 minutes.  Think about what will happen to the air temperature in the bottle as it is exposed to the sun.  Observe the inner surface of the bottle and the bottom of the funnel (we observed some condensation on the sides of the bottle but none on the funnel). (photo 1)
2. Put some ice cubes in the funnel and observe for 10 minutes.  Think about what's happening to the air temperate around the bottom of the funnel. (photo 2)
3. After 10 minutes we observed condensation on the bottom of the funnel as well as on the sides of the bottle. (photo 3)

3) How raindrops form

Another simple and potentially safer way (compared to experiment 1) to observe "raindrops" forming.  This simple experiment is done by pouring enough water into a jar to cover the bottom, then place a few ice cubes on the inside of the lid and put it over the mouth of the jar.  After 10 minutes you'll see water droplets forming on the underside of the lid.  It works on the same principle as experiment 1: water vapour (from the room-temperate water at the base of the jar) rises in the jar then condenses as it touches the cool underside of the lid.


4) How water droplets gather in clouds

This experiment expands on the previous one (experiment 3).  Tiger first squeezed many separate drops of water onto the inside of a plastic lid, then quickly turned the lid over.  He then used the tip of a pencil to move the tiny drops of water together.  What he observed was the drops seemed to pull one another together to form larger drops.  When the drops are quite big, they fell.

The attraction of the water droplets is due to water molecules having a positive and negative side, similar to how magnets attract each other at opposite poles.


5) How the Water Cycle Purifies Salt Water

Procedure:

1. Stir 1 tsp of salt into a glass of clean water.  Dip your fingertip into the salt water and taste it. (photo 1)
2. Add several drops of food colouring (we used red, blue, and green) into the salt water and stir it well. (photo 2)
3. Put the cup in a ziplock bag and zip the bag up.  Place them in the sun.  Observe the bag every 5 minutes for any changes. (photo 3)
4. After 15 minutes, we observed some colourless condensation inside the bag.   We also tasted it and found it to be tasteless. (photo 4)

Field Trip
We attended a workshop at a water treatment plant where the children were given a quick overview of the water cycle.  As the workshop was conducted at a water treatment plant, the water cycle exercise included an extended part about how water is collected and treated before becoming clean enough to come out of taps in people's homes.

The children also spent some time investigating changes in the types of organisms found in rivers and water supply due to changes in the level of pollution/industrialisation over time.

Next, it was time to head outside for a tour of the premise. 

A disused filter bed.  You can still see the water tank and pipe from Victorian times.

Much of what we saw were historical -- what the Victorians used for filtering the water supply to London.  For example, we went to an area called the Central Wellhead, which was where the cleaned water (after flowing through the pipes onto the filter beds from the surrounding reservoirs) was stored before being pumped into the water mains.

What I found to be most interesting was seeing an area of preserved filter beds.  The centre has allocated several beds to be preseved in different stages to show they changed over time.

Open Water - This filter bed looks much as it did when it was actively being used.

5 years on - When the filter bed was abandoned, the water level began to drop.

10 years and more - As more sand and gravel was exposed, the plant cover become more densed.

Deeper water - Not all the water drained away from the filter beds.  Tall water plants like reeds will grow where deep pools of water are retained.  Reed beds create a different type of habitat for birds.

25 years and more - Much of the water would have drained away, causing a wet meadow to develop.

30 years on - If the filter beds were no longer managed in any way, ash, willow, and elder trees would eventually grow on them, thus creating a woodland habitat.

The children were shown a simplified version of the filtration process using soil, bottle and water.  I wanted Tiger to conduct the experiment himself rather than passively watch someone else do it, so we did the same experiment when we got home:

Procedure:

1. Use the same bottle as in experiment 2, but this time remove the lid and cover the inside of the funnel with a piece of coffee filter paper. (photo 1)
2. Fill the coffee filter paper about 3/4 ways to the top with sand. (photo 2)
3. Dampen the sand with some clean water. (photo 3)
4. Mix soil and water together a jar. (photo 4)
5. Pour the muddy mixture through the sand carefully. (photo 5)
6. Observe the clean(ish) water being filtered into the bottle. (photo 6)

By conducting this simple experiment at home, we could see the filtration process up-close.  Even though we knew what result to expect, we still found it fascinating to see muddy water become clear water collected in the bottle.

This post is linked up to:

1. Look What We Did
2. History and Geography Meme #92
3. Collage Friday: Signs of Fall
4. Entertaining and Educational - Sept 27
5. Field Trip Friday Link Up
6. Homeschool Review and Resource Link-Up
7. Weekly Wrap-up: The One with a Little Encouragement
8. Science Sunday: Learning about Muscles
9. Hip Homeschool Hop - 10/1/13