It is a simple and easy Fun Friday experiment today – how to make an ocean in a bottle
All you need for this experiment is…
an empty clear plastic bottle (a 1 or 2L soft drink bottle will work fine)
cooking oil (any kind)
Blue food colouring
What you do…
Using the funnel fill the plastic bottle about one third full with water
Add a few drops of food colouring to colour the water blue
Using the funnel again fill the bottle with the oil (you will notice that the water and oil will quickly settle into two separate layers)
Close the lid tightly on the bottle and turn the bottle on its side
The water layer will be on the bottom of the bottle
If you rock the bottle from side to side you can create a wave like motion of the water, looking just like a little ocean in a bottle; see what kind of waves you can make!
How does it work…
This is a good experiment to explain density. The oil is less dense than the water so it will sit on top of the water, creating two separate layers. The layer of oil keeps the water contained within the bottom half of the water and makes the movement of the water look like waves where the two liquids meet.
I have discussed density in more detail in this previous post as well as sharing lots more density experiments.
If you get bored of your ocean in a bottle, why not stand it upright again and add some Alka Seltzer tablets to instantly turn it into a lava lamp!
Spring does not officially arrive in the Northern Hemisphere this year until March 20 at 16.47 GMT, the Spring Equinox – but when does Spring start for you?
The Sun FINALLY came out this week. It was a long, long winter and we all needed to feel a little of its warmth. To most of us in Ireland it has been spring since the 1st of February but this new boost has sent the conversations about spring into overdrive at the school gate. We are all more than ready to embrace it but no one wants to hear that, to some, it is not even spring yet! Here in Ireland we seem to live in a bubble when it comes to the seasons as much of the rest of the Northern Hemisphere will tell you it is not Spring until the Equinox, which this year will occur at 16.57 (GMT) on March 20th.
In Ireland spring usually means people abandon their clothing in a rapid and frenzied manner.Or, to be more accurate, it means the sighting of a lot of tee shirts and shorts and the accumulated exposure of acres of alabaster skin. It’s a wonder the glow cannot be seen from space.
A SHORT GEOGRAPHICAL LOOK AT HOW WE DEFINE SPRING
To be honest I was a little surprised to learn that most of the World is celebrating the start of a season while we Irish are smack bang in the middle of it! I took to twitter and Facebook to find out what people really thought and was delighted with the variety of responses we got.
In Ireland we learn at school that spring starts 1st February. Many people said the biggest problem they had with this was that it pushes August into autumn so most Irish seem to either amend the seasons to a four month summer or they mentally move the seasons on a month. We Irish are not afraid to bend the rules to suit ourselves!
Many Irish people follow the Celtic calendar which also says spring starts on the 1st of February. This coincides with the arrival of certain seasonal plants and the spring lamb.
Once we move outside of Ireland it would seem that the rest of the Northern Hemisphere shift the seasons on a little. Our nearest neighbours in the UK start spring on 1st March.
If we move further West into France and the rest of Europe it seems the Spring Equinox is generally held as the beginning of the season.
In the USA the Spring Equinox is the official start of spring although many will hold the 1st March as an acceptable alternative.
My favourite response to the question of “When does spring start for you?” was this one…
My husband says it’s Spring when we stop making stew once a week!
An equinox is an astronomical phenomenon – a time on Earth when we experience almost equal day and night. There are two equinoxes in our calendar year, one in March (between 19th and 21st) and one in September (between 20th and 23rd). The March one is referred to as the Spring (vernal) equinox in the Northern hemisphere and the September one is the Autumn equinox.
These are reversed in the Southern hemisphere.
The word Equinox literally means equal night derived from the Latin words “equi” (equal) and “nox” (night).
HOW DOES IT WORK EXACTLY?
The equinox refers to a time when there is almost equal day and night in most parts of the World. On the Equinox the centre of the Sun will be directly above the Earth’s equator at noon.
The Northern and Southern hemispheres will be equally illuminates at this moment. http://en.wikipedia.org/wiki/Equinox
A LITTLE MORE DETAIL…
To better understand the seasons we need to look at the movement of the Earth within its celestial space.
Firstly, the Earth rotates on its own (Polar) axis every 24 hours. Thus different parts of the Earth are facing towards the Sun at different stages of the day – this is what makes day and night.
The Earth also travels around the Sun once every 365.25 days (or 365.24219 days to be more exact) – that explains a complete year on Earth.
I hope all this isn’t making you dizzy as there is a third factor to take into account and this is the factor that accounts for the seasons; The Earth is actually tilted on its own axis by 23.5 degrees. This tilt remains constant as the Earth orbits the Sun. Therefore at different times during this orbit the Northern or Southern hemispheres will gain more Sunlight as they are tilted more towards the Sun.
The Equinoxes (Spring and Autumnal) are the only times during the year when the Earth’s 23.5 degree axis is not tilted towards or away from the Sun. At these times in the year the Sun sits exactly over the equator.
WHY DOES THE EXACT TIME OF THE EQUINOX DIFFER EACH YEAR?
Our year is governed by how long it takes the Earth to orbit the Sun. By the Gregorian calendar there are 365 days in a year. However this is not quite true as mentioned above, a year is actually 365.25 days in length (the actual duration of a full orbit of the Sun by the Earth). We fix the error by adding a Leap Year in every four years.
This does not completely fix the timing for the equinoxes however which will occur six hours later every year. The Gregorian calendar does manage to confine the timing of the equinox to within the same few days. By this calendar the equinox will occur at the exact same time every 400 years.
SOME COOL PLACES TO BE ON THE EQUINOX…
If you are standing at the North Pole on the Spring Equinox you will see the Sun start to peep over the horizon, signalling the end of six months or darkness and marking the start of six months of daylight.
If you are standing at the South Pole on the Spring Equinox the opposite is true.
If you are standing on the Equator at noon on the Equinox you will observe the Sun exactly overhead.
WHAT DOES MOTHER NATURE HAVE TO SAY ABOUT ALL THIS?
If, like me you find this scientific definition of spring hard to take in, don’t worry, Nature seems to have its own definition of spring. I do not think the emerging buds or the territorial birds are too bothered about when the Sun might sit exactly over the Equator.
To them spring is in full throttle and to me it is too!
How did you get on with last week’s Mystery Creature? Did you get it?… I admit there was a trick to it as it was a hybrid animal… a cross between a polar bear and a grizzly… often referred to as a GROLAR or a PRIZZLY or a NANULAK.
Although this grizzly-polar bear hybrid is a rarity it has been found in captivity BUT also as a natural crossing in the wild.
In 2006 the first confirmation of a grizzly-polar bear hybrid was determined by DNA testing.
In 2010 the first second-generation hybrid was confirmed (again in the wild); DNA analysis revealed the bear to be the offspring of a grizzly-polar hybrid mother and a grizzly father.
Their body size is smaller than the polar bear but larger than the grizzly.
Their heads are broad like the grizzly’s but their faces are long and narrow like the polar bear.
Their necks are longer like the polar bear but their backs are hunched behind the shoulder just like the grizzly.
The soles of their feet are partially covered in hair: the polar bear’s soles are insulated with hair while the grizzly’s are bare.
Not surprisingly this pairing of grizzly with polar bear is thought to be a result of global warming. Melting ice caps are forcing Polar bears to remain on land while some grizzly bears are being found in more Northern regions due to temperature increase and destruction of their habitat . The two species are more likely to encounter each other under these new living conditions. What is even more alarming is the reporting of an increased number of these hybrid animals, a fact that would likely endanger the future existence of both bears.
If you have ever wondered about the science of pancakes, their history, why they are round or even the formula for the perfect pancake flip then read on!
I know that pancakes Tuesday is late this year but it still seems to have come around awfully quickly. In this house the pancake does not just feature once a year but every weekend and with that kind of frequency we have covered a lot of questions about this not so humble food.
So if you have ever wondered about the history of the pancake, the science of getting them just right, why they are round or even the formula for the perfect pancake flip (L = 4 H /P- D / 2 if you’re interested) then read on!
…..”WHAT IS THE SCIENCE BEHIND A GOOD PANCAKE, AND WHO’S IDEA WAS IT?”…..
A BIT OF HISTORY…
So, before I delve into the science behind the PERFECT PANCAKE, I thought I’d look at a little bit of history first. The pancake as we know it seems to be accredited to the ancient Greeks, who in the 6th century started combining ground wheat with olive oil, honey and milk – and so the first pancake was born. If we expand on our concept of what a pancake really is we could look back further still to the process of making flat bread from ground grains and nuts mixed with milk or water, dating back to the neolithic period.
WHAT DO WE FIND IN A MODERN PANCAKE?
If we start within Europe a modern pancake can be classified as the round flat variety similar to the french crepe which contains some form of flour, and a liquid such as milk or water. These flat pancakes usually also contain eggs and butter, and sugar in the sweetened variety. Then we also have the thicker, fluffier pancakes that contain a raising agent, the name and variation of these include drop scones, Scottish pancakes and of course the well know buttermilk pancakes that are most common in America.
In our house the three most common pancakes made are the buttermilk pancakes, drop scones and the sweet flat crepe like ones.
WHAT GOES INTO A PANCAKE…
If we take a closer look at the primary ingredients we begin to see the complexity and science that really goes into making these delights:
FLOUR… this ingredient can be considered the backbone of the pancake as it provides structure
SUGAR….as well as adding the nice sweet taste and contributing to the colour of the pancake, sugar also keeps the pancake from getting to thick and stodgy
EGGS…. the proteins in the eggs add to the structure of the pancake and to the overall flavour
BUTTER/FAT… as with the sugar, the fats keep the pancake tender and prevent them becoming overly stodgy
MILK/WATER… the liquid portion of the pancake adds to the structure and is necessary for certain chemical reactions to occur
RAISING AGENT… as the name suggests, these agents help raise the pancake, making them light and fluffy
You can of course find many varieties with their own local changes and substitutes, potatoes are commonly used as the starch ingredient instead of flour.
First lets take a look at the thin flat pancake or crepe… in this case we will assume they contain flour, milk and sugar. From the above list we can now predict that the flour is the body of the pancake, it provides the structure, but how does it do this? There are two proteins found in flour called glutenin and gliadin. When moisture is added to flour (in this case the milk) these two proteins link together to form gluten. Gluten is a “sticky” protein, this stickiness allows it to form a network and it is this that adds structure to the batter. Finally we come to the sugar which caramelizes with the heat adding sweetness to the mix and contributing to the colour of the pancake as it cooks. The sugar also prevents the pancakes becoming too thick and stodgy by reducing the amount of gluten produced.
So now we move on to the thicker pancakes; the main difference with these is that they contain a raising agent! Yeast is a biological raising agent used in some baking, it produces carbon dioxide gas while digesting sugar and this gas forms tiny bubbles within the yeast. When heat is added during baking these bubbles expand making the bread/cake “rise”.
The main drawback with baking with yeast is that it requires time and who really wants to wait too long for their breakfast? That is why, when using raising agents in pancake mixtures, we substitute the yeast for bread soda and/or baking powder; but who can really tell what the difference is between these two?
Bread soda (also known as baking soda) is pure sodium bicarbonate. Baking powder contains bread soda but it also contains a powdered acid (usually cream of tartar – potassium bitartrate). Bread soda is an alkali/base and will therefore react with an acid (such as the buttermilk used in pancake batter) producing salt, water and carbon dioxide gas…
BREAD SODA + ACID —–> SALT + H20 + CO2
This carbon dioxide gas gets trapped in thousands of tiny bubbles within the gluten making the pancake batter rise on cooking into light and fluffy wonders! (The same process as with the yeast but a lot quicker).
The baking powder has the added advantage of having the acid already present, so once a liquid is added the dry acid and alkali can react in the same manner as above.
So now that we are starting to understand the science of it all how do we use this knowledge to make the best pancakes. before we jump into this one we first have to consider the science of flavour and odour!
THE SCIENCE OF FLAVOUR
The Maillard reaction describes a chemical reaction requiring certain amino acids and sugars and the addition of heat to produce the molecules responsible for the odours and flavour of food. Now there is a science worth studying!
So what does this have to do with our pancakes? Well, Maillard reactions work best in alkali conditions so bread soda is a definite plus is making golden tasty treats. HOWEVER, add too much bread soda and the pancake will brown too quickly and will have an acrid burnt flavour, not to mention the unpleasant taste produced from the left over breadsoda. It is trickier than we think and yes, of course, someone has already done the science bit for us to work out the ideal amount of bread soda required.
WE ARE HUNGRY – SPEED IT UP
You will be glad to hear that speed is recommended when preping pancakes; Although it is good to allow the batter sit for a few minutes to allow the gluten to “relax” (build up a sufficient network) it has been shown that if left too long the bubbles will have burst and the pancakes will be flat and dense once cooked.
SCIENCE IN MY KITCHEN
I decided I had to try some of this pancake science out for myself so turned to my original buttermilk pancake mix from the wonderful NIGELLA LAWSON. This recipe actually uses both baking soda and baking powder (I omitted the banana). I decided to test out two theories…
1. Does the amount of bread soda determine the colour and flavour of the pancake?
2. Does the length of time the batter is left standing really make that much of a difference?
To keep it simple, I decided to keep everything else (including the amount of baking powder) constant.
So I donned my apron in favour of my labcoat and I set to work. I prepared the basic batter mix excluding the addition of bread soda. To digress for a moment, I also followed another golden pancake rule – not to over-mix the batter (a few small lumps of flour allows it better absorb the liquid and produce gluten).
I divided my basic batter mix between four bowls and then added different amounts of bread soda to each (the first bowl had no bread soda, the second had half the recommended amount, the third had the recommended amount and the fourth had double what was recommended!). Then I let the batter sit for five minutes before cooking the pancakes.
Here are my results… the pancake on the top left had no bread soda, top right had 1/2 the recommended amount, bottom left had the ideal amount and bottom right had twice the recommended amount. You can see how the pancake gets darker with the addition of more bread soda, with the last one being just a bit too dark. The taste test revealed that the one on the bottom left had the best taste (and texture) and that the one with the most bread soda had that unpleasant taste of bread soda!
To investigate my second question I left the same pancake batters sit for two hours before cooking them. As you can see the pancakes cooked after two hours were indeed a lot less light and fluffy and were a bit soggy inside!
WHY ARE PANCAKES ROUND?
Pancakes are round for two main reasons: gravity and surface tension. Assuming that the pancake pan is flat then once the batter is added gravity will pull on all parts of the batter uniformly in all directions, pulling it out into a round shape. Surface tension pulls evenly on the edges keeping them restrained into the round shape.
According to University Professor of Mathematics Frank Smith, the simple mathematical formula for the perfect flip is: L = 4 H /P- D / 2
(L = hand distance from inner edge of the pancake / H = height of flip / D = diameter of pancake)
Dr. Tungate, a senior physics lecturer at Birmingham University, found that “a pancake should be flipped into the air at a speed of 10 miles-an-hour, which means that it takes less than .5 of a second to reach the top of its trajectory.”
AND THEN THERE IS THE SCIENCE OF WHAT YOU ACTUALLY PUT ON YOUR PANCAKES…
… but I think that is a whole other blog! So whatever toppings you choose I hope you enjoy your pancakes today!!
And if you still want more….HERE IS AN EXPERIMENT YOU CAN TRY….
This experiment shows two fun ways of inflating balloons, kids will love it, it’s easy to do and it teaches some kitchen science… like the difference between using yeast and bread soda as raising agents in baking!