Hey Blog! This post is about an amazing science opportunity in Sheffield I went to a few weeks ago!
Last year, I told you about an initiative called Sparking STEM. Run by Amanda, this project offers in-person science practicals for children from starting learning science through to GCSEs and iGCSEs. If you look at Science Experiments and Food Testing – I wrote about one of the two sessions I attended in that post. However, this year I have done a further five sessions, which are what I will now relate to you.
Microscopy. We used light microscopes to look in more detail at some samples, and learnt how to use a proper microscope. I do not have a proper, high-quality/power one of my own as yet, so this was a good chance to try one out. Light microscopes use lenses to refract and reflect light back into the lens to make the image appear larger – thus making it easier to see small details. It’s astonishing how much detail there is in everything when you start looking! Even in something that looks perfectly smooth, there are tiny scratches and shiny patches. I would love a microscope to test out all sorts of different materials to see what they are made of.
Force and Extension. This is a subject which uses Hooke’s Law – Hooke being a contemporary of Newton and an investigator of how much force applied changes the shape of the object. His law says that F ∝ x, or more accurately, F = k x. Force applied is proportional to the extension of a spring, and is equivalent to the extension times the spring constant (stiffness). However, there is a limit to the law, like when you stretch the slinky too far and it refuses to go back to normal. Yes, we’ve all done that. Most upsetting. That is when the object is irreparably stretched into a shape and Hooke’s Law no longer functions – which makes for interesting graphs!
Respiration. This is one of the most important formulae for all life on earth and together these two make the most important bit of chemistry in biology (which is why you can’t teach science disciplines separately and therefore why I’m trying to do all three sciences!). Glucose (the simplest sugar) plus oxygen makes carbon dioxide plus water or, in its balanced chemical symbol form: C6H12O6 + 6O2 = 6CO2 + 6H2O, releasing energy in the process, which powers all our functions and our lives. This means the pH value in the test tube changes, and we can measure to what degree it does by a precise pH indicator. By examining the change in colour of the indicator solution, we can see whether the pH changes and thus whether respiration has occurred. Of course, only living things respire – it is one of the categories for a living organism to fulfil – so only the living things in the test tubes changed the pH. In all, a very interesting practical!
Osmosis. This is like diffusion but only with water particles and always across a membrane. Best demonstrated by leaving potato slices in water and seeing them swell with the water that they absorb to try and equalise the water content in and out of the potato. Osmosis must be considered by farmers when they fertilise a crop – if there is an excess of fertiliser, the water in the plant will osmose (is that a word?) out of the plant to balance the water : nutrient ratio inside and outside the plant – potentially causing wilting. This is a universal principle that applies to many things – almost all substances and some forms of energy will try to equalise to their surroundings. Heat behaves this way; electric charge behaves similarly (because there are opposite charges, they try to neutralise); and particles also do this, whether water (therefore making it osmosis) or other molecules (therefore showing diffusion). Even though it can be proved purely scientifically and logically, it belies a great truth about the universe and how all things exist in balance.
Lung dissection. If you don’t like reading about chopping up body parts stop now and skip to the end: this was a real dissection, on sheep lungs. While slightly disturbing, it was important learning: how you breathe. We all need oxygen for respiration to release energy (as seen above) but instead of being a chemical process, breathing is a mechanical one. We physically (but not consciously) pull down our diaphragms, making room in the chest cavity, which pulls air into the lungs. Air rushes down the trachea, into bronchi and then bronchioles (think plumbing) then reaching the alveoli, where different gases for respiration are swapped. This enables us to keep on living. Yay! There is something profound about seeing the last breath of a sheep in the air bubbles in the alveoli, but rather amusing about seeing lung tissue float to the surface of a beaker when all other tissues sink to the bottom (because of the air content). I’m glad I attended; it’s important to know how the body works, even if you need to cut up a sheep to do so, and rounds off the post nicely – biology, or any science, needs practice to understand properly. Who knows what experiments this mad scientist might get up to next?!
