Melting Ice and Ocean Water Density

The modern ocean moves like a giant conveyor belt. In winter, as ice is forming in the North Atlantic sea, salt is pushed out of the ice creating a layer of water that is very salty and very cold. Because cold water is more dense than warm water, this layer sinks to the deep ocean. This water enters a current that carries it to the Pacific Ocean where it warms and rises to the surface before travelling back to the North Atlantic where it cools and sinks again. If a large amount of fresh water is added to this system, the conveyor belt could slow because freshwater is less dense than salty water and would not be able to sink to flow through the deep ocean.

Make a video of yourself performing the experiment. After finishing the activity, you can compare the situations in the cups to the "real" ocean.

Materials you will need

· 2x glass jugs or bowls (same size for both)

· Salt

· Timer (stopwatch / timing app on a phone)

· Ice chips (500ml in the beaker)

· Liquid food dye

Here is your challenge

1. Half fill the two glass jugs/bowls with room temperature water and several drops of food dye. Stir salt (about 3 tablespoons) into only one of the bowls until it is completely dissolved.
2. Place the same amount of ice chips into both jugs/bowls and start a stopwatch/note the time.
3. When it becomes obvious that one is indeed melting faster, a drop of food dye can be added on each of the ice cubes to colour the melt water.
4. Record the time until each of the ice cubes has melted completely.

Note: Before you start your experiment, make a prediction which ice cube will melt faster, the one in salt water or the one in fresh water? Why?

What to submit

1. Make a video (max 30 seconds): show us your experimental setup, and answer: which one melted faster? why? and why is this important in terms of ocean circulation?
2. Post your video to Instagram and tag @ScienceANU (not #hashtag). If you don't have Instagram or would prefer to email us, then just email your photo and caption to science@anu.edu.au. Note: make sure to turn off your “Private account” setting on Instagram before posting your submission and tag us. You can turn it back on soon after you receive our confirmation.
3. The week one challenge submission closes on 11.59pm on Sunday 7th November of your local time.

The winner will be announced on Tuesday 9^th November. The winning entry will be posted to our Facebook and Instagram and on the website. The winner will be notified by email. Other submissions may be included in an Instagram story.

Winner: Riley

This week we have two challenges created for you. You can complete one or both. To be in the running for a prize this week you must complete just one of the challenges, but to double your chances of winning complete both!

This week’s submissions close at 11.59pm on Sunday 14th November of your local time. The winner for both challenges will be announced on Tuesday 16th November. Follow us on the Facebook and Instagram @ScienceANU to check out the last week's winning entries and other submissions on Tuesday 9 Nov. The winners will also be notified by email.

Option #1: Designing a solar car

Here at ANU, we are proud to have the ANU Solar Racing Team who compete in the Bridgestone World Solar Challenge every 2 years. They fund, design, build and race a solar car. In the challenger class, the goal is to go as fast as possible. When building a car like this, there are many important design considerations to make in order to maximise the car’s efficiency. When building a car like this, there are many important design considerations to make in order to maximise the car’s efficiency. Aspects of the car like the number of wheels, the area of the solar array, the shape of the occupant cell are all carefully thought out.

Here is your challenge

1. Do some research into solar cars, have a look at ANU Solar Racing at ANU Solar Racing or other cars in the BWSC.
2. Make a drawing of a solar car of your design. Include some labels and size measurements.

What to submit

1. Take a photo of yourself with your solar car design.
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au.

Option #2: Biodiversity Challenge

Understanding biodiversity is increasingly important as climate change affects the habitats of many species. This is an area where citizen science – where scientists use data collected by ordinary citizens – can have a big role. This allows scientists to monitor biodiversity in local habitats on a much larger scale than they could themselves.

Here is your challenge

1. Download the iNaturalist app (it’s free).
2. Find wildlife in your local area, and find 5 different species and aim for as much diversity as possible.
3. Use iNaturalist to take a picture of each species you find and record its location. Your 5 species should include:
   • At least one plant
   • At least one invertebrate
   • At least one vertebrate.
4. Use iNaturalist to identify each species (or come up with your best guess if the identification is uncertain). If you wish, you can share your observations on iNaturalist so that scientists can access them.

Note: if you have trouble downloading/using this application, it’s all good, you can still participate in this challenge by following the submission instruction below.

What to submit

1. Create a 1-page collage of your photos and label each photo with the species name and whether each species is native to Australia or introduced. For the students in India, the same rule applies but identifying species native to India or introduced.
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au.

This week you also have two challenges to choose from.

The submissions for both challenges close at 11.59pm on Sunday 21st November of your local time. The winners will be announced on Tuesday 23rd November.

Option #1: Making models of molecules

The molecules that are the building blocks of everything in the world (including us) have a range of particular shapes that describe how they link together.  For example, a water molecule known as H2O is made up of 2 hydrogen atoms and 1 oxygen atom. Water will always have 2 times the number of hydrogen atoms as oxygen atoms.

Here is your Challenge

1. Here are the chemical formulae of six molecules: CO2 (carbon dioxide), BF3 (boron trifluoride), NH3  (Ammonia), CH4 (methane), PF5 (Phosphorus pentafluoride) and SF6 (Sulfur hexafluoride)
2. Choose one of these molecules and Google it to learn about its 3D structure.
3. Once you have researched your molecule, use materials that you can find at home to make a 3D model of it (As examples, you could use marshmallows and toothpicks, or flowers with their stems poked into a tomato – see how inventive you can be!)   

What to submit

1. Send us a photo of your 3D creation of your chosen molecule, in the photo please also tell us the formula of the molecule and what kind of 3D structure it has (For example, O3 (Ozone) is a trigonal planar molecule, for help with identifying molecule structure check out this link).
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au. 

Option #2: Hair dryer ping pong ball levitation

Ever made a ball hover? Wonder why it is hovering?

It’s because the air pushes up on the ball, and the force of gravity pulls down on the ball – where those forces two balance is where the ball hovers. The ball also stays hovering because air rushing past the ball to its sides and curls around the ball holding it in place like two cupping hands. When we tilt the blower those cupping hands of air hold it up.

You will need

• Hair dryer. CAUTION: Hairdryer needs to set on cool air not hot.
• Ping pong ball. Don’t have a ping pong ball? That’s okay! See what else you have around the house that you can get to hover in your air stream. This experiment can even be done with a leaf blower and inflatable ball for a more extravagant outcome!

Here is your challenge

1. Keep hair drier blow cool air. If your dryer doesn’t have this setting, take care the ball (or other item) doesn’t get too hot.
2. Turn on the blower aiming it straight up and place the ball about 10cm above in the stream of air – it should start to hover!

What to submit

1. Take a photograph of you with your object as it hovers.
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au.

This week we have also got two challenges for you. We will have one winner for each challenge, again you can choose to complete both challenges or just one of them. We are having so much fun viewing all your submissions, we can’t wait to see what you submit this week!

This week’s submissions close at 11.59pm on Sunday 28th November of your local time. The winners will be announced on Tuesday 30th November.

Option #1: Working model of the lungs

Take a deep breath. In through the nose, out through the mouth. As you breathe in, your lungs fill with air and expand, causing your chest and stomach to rise. As you breathe out, the air exits your lungs, and they deflate. Most of us repeat this process approximately 22,000 times a day, usually without thinking about it.

You will need

• 1 x empty 1-liter bottle
• 3 x balloons
• 2 x straws
• Strong tape
• Play-dough, clay, blu tack (anything you can find to make an airtight seal)

Here is your challenge

1. Put the neck of a balloon around the end of each of the two straws and tape it securely on (you should have two straws each with a balloon on the end).
2. Cut the bottom off your 1-liter bottle.
3. Put the two straws inside the bottle with the balloon end inside the bottle, and the other end of the straws sticking through the neck of the bottle.
4. Use your play-dough, clay, blu tack, to create an airtight seal around the mouth of the bottle where the two straws are sticking out. You don’t want any air to get out other than what comes through the straws.
5. Tie the opening of the third balloon (where you would inflate the balloon) and cut the top part off (the round part of the balloon itself).
6. Take this balloon and stretch the opening you made over the opening at the bottom of the 1-liter bottle and tape this balloon tightly in place.
7. Pull on the balloon you have taped to the bottom of your bottle. Your balloons inside should inflate. Gently release the balloon and your balloons inside should deflate. You have made a working model of the lungs!

What to submit 

1. Send us a photo or video of your working lungs, in the photo or video please also share your favorite fact about the lungs.  
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au .

Option #2: Weathering, erosion and deposition experiment

Weathering, erosion and deposition are constantly changing the shape of our environment. Weathering breaks down the Earth's surface, erosion moves the weathered rock and deposition is when that sediment settles in a new location.

You will need

• Damp sand
• Water jug
• Baking tray (a few centimetres deep)
• Something to raise one side of the pan (e.g. a book)
• Tea towel (or do the experiment outside and you won’t need this!)

Your challenge

1. Spread ~1-2cm thickness of the damp sand onto one half of the baking tray – you can even create your own topography by building hills and valleys with the sand!
2. Prop up one end of the baking tray to create a small slope.
3. Place 2-3 ice cubes in the top corners of the baking tray in a section of flat sand.
4. Create a narrow river bed in the sand from the top of the baking tray to the bottom of your sand covering. Do this by running your finger through the damp sand.
5. Pour a stream water from the water jug gently into the top of your river. Observe how the water erodes the sides (called the banks) of the river and transports the sand down-stream. Once you have observed this erosion, stop pouring and observe the sediment that has been deposited. Is there a difference in the size of the sediment that has been transported further “down-stream”?

What to submit

1. Send us a photo or video of your eroded sand, in the photo or video please answer the question “is there a difference in the size of the sediment that has been transported further down-stream? Why has this happened?”
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au .

This week your two challenges are a crypto caption challenge and a memory challenge.

The submissions close at 11.59pm on Sunday 5th December of your local time. The winners will be announced on Tuesday 7th December on our Instagram and this website.

Option #1: Crypto captions

Cryptography and codes have been used throughout history to keep secret messages safe from eavesdroppers. They take a message you want to send, and convert it into a jumbled message, called a ciphertext, that can’t be understood without reversing the process. 

As time goes on, people will discover ways of breaking the old codes, and so they are replaced by new, stronger codes. Modern codes operate not on letters and words, but on bits and bytes inside computers. To keep it simple, we’ll be sticking with just jumbling letters this time. 

Your challenge is simply to follow the instructions. Filling out this table may help:

Here is your challenge

1. Decode instructions 2 and 3.
2. UOHRHMTJUO J NWTFWN HI HXAWKRN (FS THPMOZQ J ZFSW), ROW IFTNR ZWRRWT HI WJKO HXAWKR NUWZZFSM HPR J EHTV ITHG ZWIR RH TFMOR. IHT WBJGUZW, FI QHP EJSRWV RH NUWZZ HPR "KHVW", QHP KHPZV PNW KPNOFHS, HSFHS, VFKW, JSV WMM, ZFCW F VFV FS GQ UOHRH.
3. ROWS, WSKTQUR ROJR EHTV PNFSM HPT KHVW. ROFN EFZZ XW HPT KJURFHS.

Tips:

The letters of the alphabet are secretly paired, and then you swap each letter with its partner in the message. To decrypt it, if you know the pairing, you just swap them again.

Without knowing the pairing, you can break it by counting the letters “frequency analysis” and swapping the most common letter with the most common letters in the English alphabet.

>> view solution

What to submit

1. Send us a photo of your decoded message (don’t forget to be creative with your submission). Photos will be judged by a panel of ASD – ANU Co-Lab.
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au.

Option #2: Working memory challenge

Working memory is a type of short-term memory that holds information temporarily. Think of it like a sticky note in your brain that allows you to remember information while you are using it. For example, you are using your working memory when your teacher asks you to carry out instructions such as “Get out your math textbook, open up to page 23, and answer question number 4”.

You will need

• Standard deck of cards
• Pen and paper
• 2 participants

Here is your challenge

Phase 1
Task 1: Person 1 shuffles the card deck and hands to person 2; Person 2 has 3 minutes of studying the cards to remember the order and cannot change the order of the cards or record information anywhere. After 3 minutes, person 2 writes down as many card values in order as they can remember. Person 1 checks person 2’s results and records the number of consecutive correct values without error. Repeat task for person 1.

Task 2: Person 1 shuffles the card deck and hands to person 2; Person 2 has 3 minutes of studying the cards to remember the order and cannot change the order of the cards or record information anywhere. After 3 minutes, person 2 writes down as many card values and corresponding suits in order as they can remember. Person 1 checks person 2’s results. Repeat task for person 1.

Phase 2
We are going to try tasks 1 and 2 again but first let's learn a little bit about “chunking”. Chunking is the process of grouping bits of information together to make them easier to remember. For example, a phone number 47113248 is hard to remember as just a strong of numbers. But, we can chunk this number into 47-11-32-48 or even 471-132-48 and the number becomes a lot easier to remember. We take the number from 8 individual numbers to 3-4 groups of information.

If you are working with a list of vocabulary words, for example, you might create small groups of words that are similar or related to one another. A shopping list might be broken down into smaller grouping based on whether the items on the list are vegetables, fruits, dairy, or grains.

Have a look at this link to learn more about chunking.

Now repeat tasks 1 and 2 using chunking strategies.

What to submit:

1. Send us a photo of your results from phase 1 and phase 2 (don’t forget to be creative with your submission).
2. Post your photo to Instagram and tag @ScienceANU, or email your photo and caption including your name to science@anu.edu.au.

This week your two challenges are an astronomy challenge measuring the speed of light in your microwave, and an environmental challenge all about frogs. Pick one or do both! You only have one more challenge after this week so let’s make it a big one! 

This week’s submissions close at 11.59pm on Sunday 12th December of your local time. The winners will be announced on Tuesday 14th December. 

Option #1: Tasty Relativity – Measuring the speed of light in your microwave

The speed of light is one of the most important, fundamental values in astrophysics. In a vacuum light travels at nearly 300,000,000 m/s, or 300,000 km/s. The current value is 299, 792, 458 m/s.

This value has been repeatedly measured in labs all across the world. However, you can measure it at home, with a microwave and something tasty. Microwaves are a form of electromagnetic radiation – light, and so we can use it to measure the speed of light.

You will need

• Microwave
• Chocolate, cheese, or marshmallows
• Microwave-safe plate or dish
• Ruler
• Calculator

Here is your challenge

1. If your microwave has a turntable, take it out as we want a plate or dish that will not move.
2. Look in your microwave, probably on the inside door or the back, for the output frequency. It will be in MHz (Mega-Hertz, 10^6 Hz). Make a note of this value for later.
3. If you are using marshmallows, create a single layer of them across the dish. If you are using cheese or chocolate, the bigger the size the better and put it on the plate.
4. Put your plate of food in the microwave and turn it on for 10 – 20 seconds. If it is too melted, or not enough, adjust the time.
5. When you remove it, you’ll notice it is not evenly melted, only certain parts. In fact, you should see a pattern in the melting that shows the wavelength power of the microwave.
6. Use your ruler to measure the distance between the melted parts of your food. Measure it in centimeters. This is half the wavelength of a microwave.
7. Use output frequency you found earlier and distance between melted points to now calculate the speed of light.
8. Answer How close to the current value of the speed of light did you get? Can you get a closer measurement and if so, what can you change to improve it?

c (speed of light) = 2 x distance (between melted spots) x frequency of microwave (in Hz)

Note: Make sure to convert your MHz microwave value to Hz (multiple the microwave value by 1,000,000)

What to submit

1. Send us a photo of your melted food along with answers to the questions above, if it’s a video, please ensure it’s under 1 minute.
2. Post your photo with caption OR video to Instagram and tag @ScienceANU, or email it including your name to science@anu.edu.au.

Option #2: Frogs and their habitat

Like many species, frog numbers are declining as human urbanization spreads and we lose natural habitats. However, even as we change the natural world, there are lots of species which adapt and live alongside us – including frogs. This challenge gives you a taste of how to identify frogs in your local area. This is important for both scientific data on biodiversity, but also our understanding of how we share our world with many other creatures – even in our own backyards.

Here is your challenge

1. Download the ‘Frog ID’ app – go to https://www.frogid.net.au/ or download from the Google Play Store or Apple Store on your phone (it’s free).
2. Take a moment to explore the app and follow the walkthrough, and download the offline content.
3. Identify 3 different areas where frogs might live. For example, near a river or wetland, a forest or bushland, urban areas such as a park, playing field or garden
4. Go to the different areas at different times of day, or after different weather events to see if you can hear any frogs. Be sure to take any notes so you can compare your findings later. Location > time of day > weather conditions
5. While in the field, use the record function if you hear a frog call.
6. Fill in the data – such as habitat and water body type. Then, see if you can identify the frog from the range of potential matches it gives. If you like, you can submit the recording to the Australian Museum through the app and they will identify it for you.
7. When you’ve explored 3 different locations, and in 3 different settings (at night or daytime, after rain) see if you can work out in your area the best place to find a frog, and what conditions you can hear them in. For example, can you hear more frogs at night, or after it has rained? In total, see if you can identify 3 different kinds of frogs in your local area.

What to submit

1. Send us a photo OR recording (max 1 min) OR video (max 1 min) including: what frog species you could hear, the conditions you found them in (you’ll get bonus points for creativity).
2. Post your submission to Instagram and tag @ScienceANU, or email it including your name to science@anu.edu.au.

You have all worked so hard and made some truly amazing submissions. So, let's have some fun for your last submission for 2021. To help you get festive and spread some joy for the holiday season, you are going to use math to make an ornament stellated icosahedron.

Our last submissions closes at 11.59pm on Sunday 19th December of your local time. The winners will be announced on Tuesday 21st December on our Instagram and website.

Festive Stellated Icosahedron
A polyhedron is a shape with many flat faces (from Greek poly- meaning "many" and -hedron meaning "face"). In geometry, an icosahedron is a polyhedron with exactly 20 faces.

Your challenge this week is to fold a stellated icosahedron out of paper. You can hang your Stellated Icosahedron on your Christmas tree, use it to decorate your room, or give it to a family or friend who helped you with your challenges over the past 7 weeks.

You will need

• Paper – use wrapping paper, paper you have decorated yourself, or whatever you have on-hand.

Here is your challenge

1. Watch a video on making an origami Stallated Icosahedron
2. Make a festive icosahedron and get folding! Your shape must have a minimum of 20 sides.

What to submit

1. Take a photo of you holding your finished stellated icosahedron. For an extra challenge, make a video of you folding your stellated icosahedron (videos should be <1 minute).
2. Post your photo and caption or video to Instagram and tag @ScienceANU, or email it including your name to science@anu.edu.au.