Learning units (Unità di Apprendimento, UdA) can be done pratically about everything. I like to start from Science.

Step 1: Map

Do the map. You do not need to be precise, throw in the map everything that comes into your mind. You can also do a mindstorm with pupils: "Lets talk about water: what do you know about it?"

Write on the blackboard the word "water" (acqua, in Italian), then with arrows link it with pupils' ideas. I like to do this before starting to write down my UdA. For example, I do brainstorming on friday, so on saturday and sunday I put together their and my ideas and write the work.

Of course this way is even more difficult and long than the way I described in Learning Unit - Air.

Step 2: Science and Maths

Linking to Language you can use the "5W":

Who
What
When
Where
Why

Who use water? All the living beings on Earth.
What is water? 2 atoms of hydrogen and 1 atom oxygen - H2O
When it was formed? At the start of Solar System / coming with comets
Where is it? Lakes (Como), rivers, oceans, seas, poles, glaciers.
Why is so important? Every life form needs water to live.

With Maths and Geometry: talk about the percentage of the different mass of water on Earth. Draw a square with 10 cm side. Divide it in 100 little squares and colour them:

97% salted water (seas and oceans) - violet
2% glaciers - white
1% drinkable waters - light blue

Talk about that only the light blue part is drinkable, the white is a "stockpile" and the violet is salted, so not usefull for our life.

Print a planisphere and ask your pupils to colour waters in the same ways as the squares.

Human beings are made of more or less 70% of water. We need water to be healthy. If the kids are in 5th class, you can talk about kidneys and make some simple experiments to explain kidney's work.

1) Take some pins and bottons, mix them in a box. Then ask pupils to divide pins from bottons. It's a diffult (and sometimes painful ;D) task to do with fingers. So, use a magnet: pins will be actracted and bottons not. This a kind of filters.

2) Take sands and rocks and mix them. Sift them: another filter.

Step 3: Science & Art

Using some modeling clay and toothpicks, do the water "Mickey Mouse" model. This is really simple and kids will love it ad remember it. I sometimes talk about Chemistry with my pupils from 3rd to 5th grades. It's not simple, but they like it, they get it like a game. We draw CO2, H2O, CH4 models, we search elements on Mendeleev's table and so on. Given it's Primary School, there's nothing too difficult.

Using water colours, paint the ocean's waters, draker on the bottom, ligther on the top. Using tempera they can paint with fingers rain and coulds.

You can use coloured salt (you can colour salt with chalks) to fill jars with the colours of the sea.

If you have the luck to teach near the sea and you can bring pupils out, bring then for a lessons on the beach. I sometimes have lesson in the school garden and we love it.... I can only imagine how could be great to teach and learn on the beach!

You can do a really big UdA only about the sea: a picture frame with cardboard, shells, sand.... musical instruments with shells.... watch "The Little Mairmaid" and talk about the adventures....

Step 4: Experiment: Water Cycle

Talk about water cycle and how it's important for life. You could make a simple experiment.

Put some water and salt in a pot. Make pupils take a sip of it and note that is not drinkable for a long time. Make the water boil, then cover it with a lid. Wait some seconds, then lift it: the water will "rain" from the lid: notice that it's no more salted.

You can do this experiment with ink instead of salt (do not take a sip of it!). The dirt water will evaporate and return clear.

Step 5: Music

As for the "UdA - Air", classical music can be usefull because the musicians wanted to reproduce the sounds of the nature, so Beethoven's "Tempest" and Vivaldi's "Four Seasons" are perfect. If you, as I, are not linked to music "only for babies" (Goccia dopo Goccia - Zecchino d'oro), you'll find a lot of pop songs to use:

In the Rain - Enya
Waiting for the Rain - Roxette
Let a Boy Cry - Gala
Acqua Azzurra, Acqua Chiara - Lucio Battisti

and so on.

You can make an instrument called "bastone della pioggia" (rain stick): take a cardboard cylinder, close one side, put in it some rice and close the other side. Moving slowing the cylinder, it will make a sound similar to rain.

And do you know that if you strike your tongue (please, help me on this term: it's when you make a "toc" sound with your tongue), the sound is similar at the falling drop, mostly if you are in 10/20 in a room making it quickly?

Step 6: Sports

The best thing is to go to the swimming pool. ;) In my school there isn't the gym (absurd, I know), so in the 2nd part of the year, my collegue brings the pupils and the swimming pool, luckly it's at 1 km from my school.

You can also use the game I presented in the UdA Air 'Ible about matter states:

Non competitive game (this is my idea) - knowing the states of the matter (solid; liquid; gas)

The pupils are parted in teams (4-5 pupils, no more);

They have to act like the molecules of the state dictated by the teacher (or one of the pupils):

gas = they run around with no order; (water)
solid = they embrace and do not move too much; (ice)
liquid = they take their hands and walk around; (vapor)

This can be done more difficult just saying "more heat" or "less heat" or something similar ("I add fire!" "I put you in the freezer" and so on) or even more difficult using the name of the state transition (evaporation; sublimation; and so on). My pupils love this game.

Step 7: Foreign Language

Use this them to teach some new words:

acqua = water
ghiaccio = ice
oceano = ocean
mare = sea
pioggia = rain
fiume = river

And, given that is so trendy, explain what "SPA" means: Salus Per Aquam (health through water). So you'll teach Latin too!

Step 8: Social Studies

It's important to teach pupils not to dirt or waste water, but also the importance of washing hands.

You can do an experiment: take a glass jar, put in some water and some dirt (plastic, dirt paper, used matchsticks, and so on). Then ask your pupils if they would drink it: of course not!

Step 9: Other Subjects

Language: poems and readings that talk about water.

Geography: problems of the people who don't have enough water.

History: wars to have the use of water supplies.

Religion: Deluge, baptism, Jesus that convert water in wine....

Let pupils watch some documentaries, as I lready said, only when they know already something about water, so they can understand better what is shown.

Free your mind and enjoy! >^.^<