This activity uses a bit of science trickery to make an object that sinks in water, float in water.
Why do things float in water?
Objects are made up of very tiny molecules. Molecules can be packed in close together like in a rock or more spread out like in bubble wrap. The positioning of molecules affects the density of an object. Objects with tightly packed molecules are more dense than those where the molecules are spread out.
Density plays a part in why some things float and some sink. Objects that are more dense than water sink and those less dense float.
Hollow things often float too as air is less dense than water. This is partly why huge heavy ships float. Another thing to consider is the shape of an object. Generally the more of the outside of an object that is touching the water the more buoyant it is. Water pushes back up against objects so the more surface area an object has the more water pushes back against it helping it to float.
When an object floats, it pushes water out of the way ( displacement ). Have you ever noticed that when you climb into a bath the water level rises? That’s because your body displaces ( moves ) the water.
This easy activity demonstrates how reducing the density of a heavy object allows it to float.
A selection of different balls, one should sink in water
A container filled with water
Balls to use:
Ping pong ball
First sort the balls into balls you think will float on water and balls you think will sink.
Do the balls which float all have something in common? Are they hollow?
Test each ball to see if your predictions are correct.
Take a ball which sank to the bottom of your container and wrap in bubble wrap.
Place the bubble wrapped ball on the surface of the water, you should find it now floats. If it doesn’t add some more bubble wrap.
Why does this happen?
Although the bubble wrap makes the ball weigh a little more, it also displaces extra water making the ball more buoyant.
The pockets of air in the bubble wrap mean that the ball and bubble wrap together are less dense than the water, which means the ball floats!
What’s the smallest amount of bubble wrap you can use to make your ball float?
Using the knowledge you’ve gained from this activity, how would you make a lemon sink?
Can you think of a different way to make the ball float? What if you made it a boat with plasticine?
James Watson and Francis Crick along with Maurice Wilkins and Rosalind Franklin discovered the structure of DNA in 1953. Before this groundbreaking discovery scientists knew that DNA carried genes which parents passed onto their offspring but didn’t know how it worked or what DNA looked like.
Rosalind Franklin produced an x-ray which helped Watson and Crick work out the double helix structure of DNA, although her contribution to this amazing discovery wasn’t acknowledged until after Crick, Watson and Wilkins received their Nobel Prize.
Did you know that 99.9% of the DNA of each person is the same? It’s just that tiny 0.1% that makes us all different! Isn’t that incredible?
What does DNA stand for?
DNA stands for deoxyribonucleic acid, it’s a long thin molecule a bit like a recipe containing instructions or code which tells cells how to behave and grow.
What is DNA made from?
DNA is made from nucleotides. There are four different nucleotides: adenine, thymine, cytosine and guanine. We call these bases and usually refer to them by the first letter of their name.
A pairs with T and G with C.
Why is DNA shaped like a double helix?
DNA consists of a 2 backbones holding together the nucleotides. The two backbones twist together giving a double helix shape with the two strands held together by hydrogen bonds between the base pairs.
DNA can copy itself by separating a bit like a zip. The newly unpaired nucelotides attract new partners building two new idential helices.
What is a gene?
A gene is a set of instructions held on a string of DNA telling a cell how to make a specific protein or enzyme molecule. The set of instructions ( or code ) is made up of codons. A codon is set of 3 nucleotides. For example a string of codons could look like this:
GAC ATC GGA AAT
Genes carry information that determines your traits ( features or characteristics that are passed on to you by your parents ).
The DNA in a gene provides instructions for making proteins which are the building blocks of everything in your body. Proteins help bodies to grow, develop and stay healthy.
What is an enzyme?
Enzymes speed up chemical reactions.
What is a chromosome?
Chromosomes are found in the nucleus of cells and are made from very long DNA molecules.
Human body cells have 23 pairs of chromosomes.
What is a genome?
All the genetic information in an organisim is called its genome. You might have heard of the Human Genome Project which aimed to sequence the entire human genone using DNA of several people to find an average sequence. The project was finished in 2001, but scientists are still working to identify single genes.
Make a DNA model
We’ve been busy creating very simple DNA models using sweets.
Liquorice sticks or other long thin candy
Something soft for the bases – we used jelly tots and jelly babies chopped in half. I tried with midget gems first but they were too hard to push the cocktail sticks through. Small marshmallows would be a good alternative too.
Remember C and G and T and A always pair up, so assign a colour to each nucleotide and add pairs of sweets to your cocktail sticks.
Attach each end of the cocktail sticks to your liquorice, spacing them evenly apart.
Once you have a long enough string, twist it to give the spiral shape of a double helix. This one is a little on the short side, so our next challenge is to make a bigger version.
With only 8 days to go until British Science Week, we’ve been busy planning lots of extra special activities for the 10 day celebration of science, technology, engineering and maths. Are you joining in this year? If you haven’t made any plans yet, it’s not too late. There are some brilliant science activity packs based around exploration and discovery for all ages available on the British Science Week website or we have some fun science ideas from last year.
I’m very excited to be working with TTS on some fun features over the next few months, starting with a fantastic competition where you can win this brilliant Science ICT Kit.
The kit contains a log-box data logger, set of rechargeable stopwatches, set of rechargeable Easi-torches, set of 6 handheld microscopes, an Easi-Scope microscope, a recordable magnifying glass and a pair of recordable binoculars. Imagine the classroom investigations you could do with that lovely lot.
To enter, complete the Rafflecopter form below – UK Entry Only
This competition is open to residents of the UK, the Channel Islands, Isle of Man and Republic of Ireland aged 18 years or over, except for those associated with the production company, their families or anyone else associated with this competition.
All information detailing how to enter this competition forms part of these terms and conditions.
All entries must be received by the advertised closing time date 12th March 2018 (23.59pm).
One entrant shall receive Science ICT Kit from TTS.
All prizes are non-transferable and there are no cash alternatives. The prize is subject to availability.
Science Sparks are responsible for the first part of the promotion, which is the publication and adjudication of the competition. All other facilities connected with the provision of the prize are the responsibility of the Promoter.
Winners are required to make contact within 28 days if a winner fails to respond a new winner will be selected.
This promotion is in no way sponsored, endorsed or administered by, or associated with, Instagram or Facebook.
My 10 year old is currently reading a book called 101 People Who Made History. When flicking through I found myself naturally drawn towards the many amazing scientists who have helped make the world what it is today with their hard work, sheer determination and passion for science and technology.
I’ve collected a few activities and simplified experiments linked to famous scientists to help children understand the concepts these inspirational people discovered.
Galileo was an astronomer, physicist, mathematician and inventor. He built his own telescope which allowed him to discover features on the surface of our moon and the moons of Jupiter!!
When Galileo was alive many people thought that the Earth was at the centre of the Universe, Galileo explained that the Earth orbits the sun (also stated by Copernicus ), a theory that got him into lots of trouble with the church. You can demonstrate this easily using our Sun, Earth and Moon demonstration.
One of Galileo’s most famous observations was that two same size objects of different weights hit the ground at the same time when dropped from the same height.This is because the force of gravity acting on both objects is the same. You can test this by dropping two identical water bottles from the same height. Empty one bottle and leave the other half full. You should find that if you drop them from the same height they hit the ground at the same time.
Nicolaus Copernicus was an astronomer born in 1473 who realised that the Earth orbits the Sun, an idea strongly opposed at the time.
The model proposed by Copernicus was called Heliocentrism, where the Sun is motionless at the centre with other planets rotating around it. Copernicus’s ideas marked the beginning of modern astronomy.
Italian Renaissance Man Leonardo Da Vinci created some of the world’s most famous art works, including the Mona Lisa and Last Supper, but he was not just an artist. Leonardo Da Vinci was also a scientist who studied anatomy, geology and flight. He kept journals full of drawings of the different subjects he was studying and often wrote his notes using a kind of shorthand he invented himself and also mirrored his writing, writing from right to left.
Caroline Herschel was the first woman to discover a comet, the first woman officially recognised in a scientific position to receive a salary and the first woman to receive honorary membership into Britain’s Royal Society.
She made a huge contributions to the field of astronomy in her lifetime, both independently and alongside her brother William Herschel.
You can learn about the structure of a comet by making a simple comet model.
As well as figuring out why objects fall to the ground and why planets orbit the Sun, Isaac Newton showed that white light is actually made up of a range of colours and used a prism to show this. Did you know the Hubble Space Telescope is based in Newton’s reflecting telescope design?
You can split white light into all the colours of the rainbow by shining a torch through a prism in a dark room. Or you can get the same effect by blowing bubbles outside. When white light shines through the film of the bubbles, it is reflected and dispersed, splitting white light into its different wave lengths and showing all the colours.
Isaac Newton also created the Laws of Motion. One brilliant way to demonstrate all three laws is to make a film canister rocket.
Charles Darwin showed that that life on Earth is the result of millions of years of gradual changes, a theory we call Evolution by Natural Selection. It means that animals best suited to their environment are more likely to survive and pass those features onto their offspring.
Darwin made his discoveries while on a 5 year voyage on a ship called HMS Beagle. He collected samples, fossils and made observations.
This activity would also br great for learning about Mary Anning. Mary was a fossil hunter who helped find some of the first dinosaur bones. Mary’s worked helped scientists form the theory of Evolution.
Louis Pasteur was a French Chemist who found that bacteria cause harmful diseases. He also discovered that bactera can be killed by boiling, a process we call Pasteurisation.
Jospeh Lister was a British doctor who believed that germs from dirty equipment and people not washing their hands were causing infections in patients after operations. He found that sterilising equipment and using antiseptics ( substances which prevent or slow the growth of micro organisms ) drastically reduced the rate of infection.
You can see how easily microorganisms spread between people by putting a little glitter and handcream on your hand and then shaking hands with someone else. You should find that the glitter spreads to their hand too. Keep shaking hands with people. How many can you infect with your glitter germs?
Wilhelm Roentgen was a German physicist who discovered X-rays. You can learn about X-rays and how they are used to detect broken bones with these easy activities.
Marie Curie was the first woman to win a Nobel Prize. She discovered two new radioactive elements and realised that radiation could be used to treat human diseases. Marie used her knowledge to improve X-ray machines, creating one that was small enough to fit in an ambulance.
Ernest Rutherfors discovered the structure of the atom, figuring out tha most of an atom’s mass is at its centre ( nucleus ) with the rest being mostly empty space. Rutherford also found that the nucleus could be broken apart if struck by another high energy particle. He created a new science known as nuclear physics.
Kids Activities Blog have a great activity where they show you how to make a model of an atom.
Watson and Crick
James Watson and Francis Crick worked together at Cambridge University studying the structure of DNA. They discovered that DNA ( Deoxyribonucleic Acid ) consists of two strands twisted together in a double helix.
Cai Lun invented paper in 105! He used the soft inner bark of a mulberry tree, bamboo fibres and water. After mixing he poured the mixture over cloth and let the water drain away. When the mixture dried it left behind paper! The invention of paper allowed discoveries to be recorded and spread much more easily.
Just before Christmas the lovely people at DUPLO sent us a box of bricks and some challenge ideas. If you read Science Sparks regularly you’ll know that we LOVE LEGO and DUPLO and use both frequently in our activities.
If you look carefully at the photos below you’ll notice some of our bricks have numbers written on them from years of using DUPLO to teach children to count, and I’ve had to clean sticky areas from many a brick that’s previously had something stuck to it. That’s got to be the sign of a much loved toy!
I remember buying my eldest daughter ( who is now 9 ) a DUPLO house for her first birthday, a set I very much enjoyed building again earlier today with my almost 1 year old. It’s lovely to have another little DUPLO builder in the house.
To celebrate all things DUPLO, we’ve put together a fun collection of our favourite DUPLO play ideas from the last few years. I’ll keep adding to the collection, so do pop back again.
DUPLO Tic Tac Toe
This was one of the the fab ideas sent to us by DUPLO which my daughter changed slightly to give each player different themed characters. This set up is Winnie the Pooh vs Toy Story!
I love Tic Tac Toe as it’s easy enough for even very young children and nice and quick for those times when you want to play a game, but don’t have much time.
Printing Patterns with DUPLO
Back when my big children were little, they loved creating patterns using paint and DUPLO bricks and people. Next on our list is to use the bricks to make pictures of flowers and trees.
DUPLO Ball Run
My 10 year old created this DUPLO ball run using DUPLO and paper to make the run down smoother. It took a few attempts, but he managed to find a way for the ball to travel all the way through without stopping.
This has been a great project as all the children have come back to it over and over again this half term, making the ball run bigger and longer each time.
Our DUPLO Monsters are a new creation for this week. You could make these symmetrical, write stories about them or draw their shadows to extend the fun further.
We made letters using DUPLO bricks and then used a crayon to run over the top to give the print of the letter on the paper.
DUPLO Ring Toss Game
Another idea sent to us by DUPLO was this great ring toss game. Ours had a festive theme, but you could easily change this for any time of year.
How about flower towers for spring?
More DUPLO Play Ideas
Can you work out how many DUPLO bricks tall you are?
We LOVE this DUPLO maze, could you make a version with several layers?
Did you ever make scratch art paper pictures as a child? I remember making them using coloured colouring pencils with black crayon over the top, they took an age to make and never worked that well. If only I’d known then that oil pastels are an amazing art resource.
Use the oil pastels to add lots of colour to one sheet of card and then rub over the top with a black oil pastel.
Once you’ve completely covered the card in black, you can create your scratch art picture.
Scratch Art Eggs - YouTube
Try using a white crayon to draw a picture on white card, you’ll need to press down very hard. Once you’ve done that, gently crayon over the top using coloured crayons. You should find the white resists the coloured crayons giving you a lovely white outline on the page.
For those days where you don’t want to be making your own scratch art paper, we highly recommend these ready made scratch art sheets from Melissa and Doug.
Have you heard about Terrific Scientific from the BBC? BBC Terrific Scientific is a fantastic primary science campaign hoping to get children to think differently about what being a real scientist is like. Here at Science Sparks we’re all about making science fun and accessible to everyone, so we think BBC Terrific Scientific is pretty awesome!
Terrific Scientific consists of ten classroom based investigations using minimal equipment. When a school has completed an investigation they send the results to both the BBC and leading universities as part of real academic studies. However, it’s not all about schools, the BBC Terrific Scientific website also has a brilliant DIY section full of exciting investigations you can carry out in your home. We’d definitely recommend having a look around and trying some out on the weekend or in half term.
BBC Terrific Scientific’s current investigation is all about POWER. The two-week challenge with the University of Edinburgh encourages children investigate how much power is used by their school. They will look for ways to improve their efficiency, find ways to change their behaviours and reduce how much electricity they use.
Once the results are in schools will be able to compare how much power they have managed to save with other schools across the UK on the BBC Terrific Scientific map.
Inspired by BBC Terrific Scientific we’ve come up with our own power activity based around simple circuits.
Before you start, please read on for some very important health and safety advice. As we’re demonstrating electricity, this activity will require adult supervision. Electricity can be extremely dangerous, so please ensure none of the wires are damaged or exposed, and ensure your hands are dry before you begin the activity. Please also make sure an adult checks the circuit before it’s switched on, and remember to always switch it off at the end of the activity.
Light up a model village - YouTube
Make a light up model street
This activity uses a model village to demonstrate how power reaches our homes and introduces the concept of an electrical circuit.
We use electricity in our homes to power lights and televisions as well as for cooking and heating so it’s very important. The electricity used to power appliances you plug in is called mains electricity.
Mains electricity can be very dangerous, never poke things into a plug socket or touch switches with wet hands.
Electricity is also used for small toys and games powered by batteries, we’re going to use batteries for our circuits.
Battery pack with wire
Crocodile clips and wires
Making a simple circuits
First let’s create a very simple circuit. A circuit always needs a source of power, we’re going to use a battery pack with wires connected to the positive (+) and negative (–) ends.
Create a circuit by placing each wire into the connector area of the lightbulb. You should find the bulb lights up. Now hold one wire slightly above the connector, you should find the bulb goes out. You’ve broken the circuit. Electricity only flows if a circuit is complete as it has to flow all the way around for the bulb to light up.
Add a switch
Switches can be used to control whether a circuit is complete or not. When a switch is open, there is a gap in the circuit which means electricity cannot travel all the way around. When a switch is closed it makes the circuit complete again allowing electricity to travel around the circuit.
You can make a very simple switch using small piece of folded paper and two paperclips. If the paper is open the paperclips do not touch, meaning there is a break in the circuit. If you close the paper, the paperclips touch which completes the circuit.
Connecting bulbs in series
You should have found that the bulb in your simple circuit was quite bright. If we add another bulb into the same circuit without increasing the power both bulbs will be dimmer than one alone. This is because the more bulbs ( or other features such as buzzers ) in a circuit the harder it is for the current to flow. There is more resistance.
If your circuits don’t work try the following:
Check your batteries work
Look for loose wires on the bulbs, the wires must be fixed in place and touching the metal part for the circuit to be complete.
Check your bulb is screwed in properly and isn’t damaged.
Did you know electricity is not stored in a battery, it is generated inside when the chemicals react with each other.
Lighting up a model street
Electricity in the home is generated by power stations, but how does it get from a power station into your house?
Pylons carry power lines from the power stations to substations closer to houses. From the substations, underground cables carry the electricity into homes.
We created a small model street to demonstrate this and to use all three circuits created above. You can see the power station in one corner, with power cables being taken to a sub station via pipe cleaner pylons. We’ve drawn lines to illustrate underground cables too.
You will need:
Small houses – use cardboard boxes or create a wooden frame.
The circuits created above
We created our houses using a wooden frame in a cube shape with cardboard attached for walls.
Our street has four houses:
One is lit with the simple circuit.
Two are lit by the series circuit ( one bulb in each house )
One has the circuit with a switch.
Turn on each circuit and watch your street light up. Do the bulbs that share a circuit look dimmer than the bulbs that are on their own?
How many houses can you light up using one circuit with the light bulbs in series?
Can you overcome the extra resistance in your series circuit by adding extra batteries? You should find the extra power makes the bulbs brighter.
What do you think of our model street? If you like the idea, take a look around the BBC Terrific Scientific website and see what else takes your fancy.
We challenge you to try one of the investigations from the DIY section on the Terrific Scientific website, maybe even with a child who thinks they don’t enjoy science activities, you might be surprised how much fun they ( and you ) have.
We know from our play dough circuits that the circuit needs to be complete for electricity to flow, but we usually want to be able to control whether electricity flows or not. This can be done using a simple switch.
How to make a simple switch
The basic circuit below has a switch made using a small piece of paper and 2 paper clips to break the flow of electricity which allows the bulb to be turned on and off.
Cut out a small rectangle shape from the paper and attach a paperclip to each end.
Set up your circuit like the one below. You should find the bulb only lights up when the paperclips touch. This is because the metal paperclips do conduct electricity but the paper does not.
Metals are good conductors of electricity , so wires are made from copper, which has the added advantage that it can be stretched thin without breaking. The wires you use are covered in a coat of plastic for safety which does not conduct electricity.
Can you add an extra bulb to your circuit? What do you notice?
We’ve been doing a lot of space themed activities recently focussing on the many famous scientists who changed people’s perception of the Universe. In the 1600s many people thought that the Earth was at the centre of the Universe, until Copernicus used mathematical models to prove that the Earth actually orbits the Sun.
We’ve used a paper plate, magnet wand and paper clip to show this.
These squishy bags are a great, mess free way to experiment with mixing colours. After we’d finished experimenting making different colours we put a sheet of card inside each paint filled bag, sealed them up again and used them to practice forming letters and numbers with our fingers.
Here at Science Sparks we’re trying to reduce the amount of plastic we use, so do wash out the bags and save for another activity once you’ve finished.
Small sealable plastic sandwich bags
Red, yellow and blue washable paint
Small sheets of cardboard/stock
Place a two small blobs of different coloured paint into each bag.
Carefully seal the bag and gently squish the colours together until they mix. You should find:
Yellow + Blue = Green
Red + Yellow = Orange
Blue + Red = Purple
Once you’ve finished experimenting place a small sheet of card inside each bag and carefully seal it up again.
Try writing letters and numbers on the surface of your bag, wipe the surface clean and then try again.
Mixing colours – why does this work?
What are primary colours?
Primary colours cannot be created by mixing other colours together.
Red, Yellow and Blue
Secondary colours are made by mixing primary colours.
Tertiary colours are made by mixing a primary colour with a secondary colour.
Always supervise small children when using paint and plastic bags