Dyeing wool in the woods by Gillian Willis

Tomorrow 19th March 2012 will be a very exciting day in the woods indeed. Helen, Lauren and I will be working together to introduce the children to the process of dyeing using natural materials. We will be dressed as witches(good, friendly witches)who make magic potions to help people. The reason behind this lesson is to show pupils that the fire can be used for a variety of reasons not just for cooking and keeping warm. They will also learn that everyday items found in the natural environment can be used as dyeing agents to produce beautiful colours. We will ask leading questions to incourage thinking about fabrics that they are wearing and how the colours came about. We will show the children how to dye wool using ewe bark, onion skins, blackberries and oak galls.They will predict what colours will be produced by each one and at the end they will see if they were correct. Fingers crossed that they will all enjoy it!!! Pics to follow!

How are snowflakes formed? - Sophie

 How are snowflakes formed?

My question is fairly simple but I did not know the answer, so here is what I found out.

Snow is formed when temperatures are low and there is moisture in the atmosphere. The moisture is in the form of tiny ice crystals. When these collide they stick together in clouds and become snowflakes. If enough ice crystals stick together they will become heavy enough to fall to the ground. Although, snowflakes will only fall when the air temperature is below 2ºC otherwise it will melt and fall as sleet or rain.

The size and make up of a snowflake depends on how many ice crystals group together and this depends by air temperatures. Dry, cool air will be small powdery snowflakes that don't stick together. However, when temperature is warmer than 0ºC, snowflakes melt around the edges and stick together to become big snowflakes. This is the best snow for making snow men!

In addition, snowflakes can occur in lots of different shapes and forms. Every snowflake is unique but will have six sides because they join together in a hexagonal structure.

Sources:

www.metoffice.gov.uk

http://chemistry.about.com/od/moleculescompounds/a/snowflake.htm

http://www.noaa.gov/features/02_monitoring/snowflakes.html

Roasted Marshmallows- by Gillian Willis.

  

Marshmallows contain a high percentage of sugar but also contain corn syrup, gelatine and corn starch. Roasting marshmallows is a fun and common practice especially around campsites although it can be done at home as well, using candles. Have you ever wondered about what actually happens when you roast a marshmallow? From my research, I will have a go at trying to explain!

When a marshmallow is placed near a flame it goes through a series of stages. As the marshmallow heats up the bonds that hold the sugar and oxygen atoms together begin to break and rearrange themselves forming water molecules and carbon dioxide gas.

As the water molecules turn to steam, the marshmallow begins to expand and tiny holes develop in the surface of the marshmallow for the steam to escape.

As the marshmallow depletes of moisture, it becomes a crispy char.  Oxygen in the air rushes to its surface and it begins to burn. A bluish flame is sometimes seen due to the carbon (from the sugar) reacting with oxygen.

  As it burns, the marshmallow goes through various colour changes. If left to burn over the fire the center will collapse and will also burn in available oxygen from the air. You will then end up with a black, residual mass of crispy char (carbonization of the sugar). Can you guess what this black mass really is??

So what’s your favourite type? Lightly toasted and golden brown? Black and charred on the outside yet gooey on the inside, or do you just prefer them straight out of the pack?

 

 

 

References:

google images

http://teachers.bsd405.org/dightmanb/biology/dailywork/unit1_part2_lesson4.pdf

Accessed: 25^th Feb. 2012

All Biochars are Not Created Equal, and How to Tell Them Apart. 2009

McLaughlin, H., Anderson, P., Shields, F., Reed, T.

Why is snow white? by Gillian Willis

Visible white light from the sun is made up of a series of wavelengths of light on the electromagnetic spectrum, that our eyes interpret as different colours. When white light hits an object, eg a yellow banana, different wavelengths of light are absorbed by the banana while yellow is reflected back to your eyes.

When you look at snow you are rarely ever  looking at one snowflake at a time, instead you tend to look at a collection of snowflakes on the ground. As light hits the snow, it is quickly reflected and scattered in many different directions due to the complex nature of the structure of each flake.

What little sunlight is absorbed by snow is absorbed equally over the wavelengths of visible light. In other words, all the different wavelengths that could be interpreted by your eyes as different colours are scattered by the snowflakes, as the light basically bounces right back out of the snow. As a result, snow takes on a white appearance.

Saying this, snow has actually been reported to be seen in  different colors!!! One famous case was reported by Charles Darwin. During one of his expeditions he noticed that the hooves of the mules were becoming stained red as they walked through the snow.The red snow was caused by the presence of certain tiny plants called algae, which had been in the athmosphere when the snow formed. In fact, some people believe that the red algae that taints snow red actually looks and tasts like watermelon!

Snow can also appear to be red if the air during the snow formation contains red dust particles. Snowflakes forming around these tainted dust particles take on a reddish colour. Red snow can sometimes be found in those parts of Europe where the air is filled with dust particles from the red sands of the Sahara Desert. I would probably not like to taste that type!!

Snow can also appear to have yellow, purple, orange or green hue.....any ideas why???

Ref.

Met Office

National Snow and Ice data Center

Gibbs, N. Science and Technology