Term 3 Summary and Reflections

In this term, I learnt about elements and compounds, solutions and suspensions, seperation techiniques, cells, and also energy.

Firstly, we learnt about elements and compounds. We were supposed to learn this last term, but were unable to due to time constraint. As a result, we had to rush through this topic and I could not really revise much about it; we learnt about elements, compounds and mixtures. I felt that this topic was fairly difficult, as memorising the different word equations for different compounds was quite tedious. Also, we had to memorise the short-forms of some elements of the Periodic Table. One thing I remembered clearly was the differences between compounds and mixtures. Some of these differences include: 

• In terms of properties, a compound has its own set of properties and does not have the properties of its elements, whereas a mixture has the same properties of the substance it is made of.
• In terms of separation, a compound cannot be broken down into simpler substances by physical means- a chemical reaction is needed to do this, whereas a mixture can easily be separated into its substances by physical means.
• In terms of preparation, a compound is made only when a chemical reaction takes place, whereby the atoms of elements are joined together, whereas a mixture can be made easily without any chemical reaction.

Periodic table of elements

Next, we learnt about solutions and suspensions. We learnt the differences between solvent, solute and solution. I was quite confused in the beginning because all three words were so identical. We also learnt the factors which affect the rate of dissolving, e.g temperature of solvent, stirring, etc. After that, we moved on to separation techniques. This includes different techiniques such as filtration, crystallisation, etc. Thankfully this topic was not really tested in the common test. I had difficulty identifying and differentiating all the different separation techniques. This is a point I must improve on.

Crystallisation

After that, we learnt about cells. I felt that this was an easy topic as I touched on it before in primary school, thus I had some prior knowledge of it. I did not have much trouble identifying the differences between plant and animal cells, etc.
Moving on, we learnt about diffusion and osmosis. Diffusion is the net movement of molecules from a region of higher concentration to a region of lower concentration. Osmosis, on the other hand, is the net movement of water molecules through a partially permeable membrane from a region of higher concentration to a region of lower concentration. Put simply, osmosis is diffusion through a partially permeable membrane. Osmosis stops when the two solutions involved are of equal water concentration.

An animation explaining osmosis

Lastly, we learnt about energy. This included digestion. Firstly, we learnt about enzymes. This included;

• Amylase- starch-> maltose
• Maltase- maltose-> glucose
• Protease- protein-> amino acids
• Lipase- fats-> glycerol+fatty acids

Again, I had to take some time to memorise all this. Next, we learnt about digestion and enzymes' effects in different parts of the digestive system. Lastly, we learnt about photosynthesis and respiration. We learnt how to test for starch (iodine test) and also the importance of photosynthesis- it makes chemical energy available to animals and removes carbon dioxide from the air. We also learnt about respiration, which occurs all the time and is a vital process for both plants and animals. Also, we learnt about aerobic respiration- the process whereby glucose is broken down in the presence of oxygen with the release of large amount of energy in living cells. This was fairly different from what I learnt in primary school; I did not know there were different kinds of respiration.

explaining enzymes

For this term's test, I scored a 76(A1). I was extremely pleased with myself for making a big jump from E8 to A1. I will strive to achieve the same result for my EOY science exam! :)

Favourite Practical

My favourite practical experiment would be the bouncy raw egg with moving waters (1P15). The experiment's objective was to demonstrate osmosis in living cells. Here are the apparatus and materials needed for the experiment;

• raw quail's egg
• dilute hydrochloric acid
• beaker
• glass rod

Here is the procedure-

Be careful- the acid is corrosive!

1. Place a quail's egg in the beaker.
2. Fill the beaker with dilute hydrochloric acid.
3. Soak the egg in the acid for about 15minutes, stirring gently with a glass rod occassionally. 
4. After 15minutes, pour the acid away from the beaker. Be careful not to touch the acid with your hands!
5. Carefully rinse the egg with tap water and examine it.

By right, the egg should feel harder to the touch as compared to how it was before the experiment. This is because osmosis has taken place- water has moved from a region of higher concentration to that of lower concentration in the egg across a partially permeable membrane.

Term 2 Summary and Reflections

In term 2, I learnt about measurements, physical quantities and units, and Kinetic Particle Theory. 

Firstly, we were taught about unit conversion. This includes units such as nano, micro, deci, etc. I was quite fascinated with all this knowledge as it seemed impossible to measure to such an accurate detail. Also, we learnt how to draw and read proper graphs. This was fairly simple to me.

Next, we learnt how to calculate density and the relationship between density, mass and volume. With this formula, I could solve most density calculations questions. However, there were still certain questions where displacement was involved, and that is also an area I did badly in in this term's test. Also, we learnt about buoyancy. I learnt that air or water can affect an object's ability to sink or float- submarines have this thing called a ballast tank which can be opened to help in sinking or floating! I could see how this applies in real life.

Relationship between mass, density and volume

Lastly, I was taught the Kinetic Particle Theory. The Kinetic Particle Theory, or KPT for short, states that matter is made up of tiny discrete particles which are in constant and random motion. Evidence for this theory is demonstrated by Brownian motion (constant and random motion of small solid particles in fluids) and diffusion (particles moving randomly from a region of higher concentration to a region of lower concentration). Furthermore, electron microscopes have taken X-ray diffraction patterns of crystals- this provides even more evidence that KPT is existent. Moving on, there is the molecular model of the three states of matter.

• For solids, particles are closely packed together in a fixed, regular pattern, occupying minimum space and resulting in high densities. They cannot move freely but vibrate about and are held in position by strong attractive forces. This also explains why solids have fixed volumes and shapes.
• For liquids, their particles are randomly arranged but slightly further apart as compared to solid particles. This is why liquids tend to have high densities. In terms of movement, particles slide past one another and are free to move about but are confined to the vessel containing it. They also have attractive forces between them, which explains why liquids have fixed volume but will take the shape of the vessels containing them.
• For gases, the particles are very far apart and are randomly arranged so they will occupy any available space. This results in them having very low densities. Gas particles have very little attraction between them and move about randomly and at high speeds. This explains why gases have no fixed volume and shape, and why they can be compressed.

After learning about this, I was quite perplexed as there was a lot of information to take in. However, I had learnt about the three states of matter in primary school, so I expected myself to take little time to memorise these facts. Despite this, I still did badly for this particular topic in the test. 

Molecular model of the three states of matter

For this term's test, I scored a 43 (D7). This was a fail and I was quite displeased. I did not do well because of the density calculations and the Kinetic Particle Theory. This was due to the fact that I did not memorise all the facts needed for KPT such as arrangement and movement of particles, etc. I will work harder next term!

Term 1 Summary and Reflections

In this first term, I learnt about science as an inquiry.

First of all, I was taught about the laboratory and the rules we should adhere to in the laboratory, such as putting on safety goggles when engaged in experiments involving fire. I was quite surprised with all this information as I was never really told about rules in the laboratory in primary school. We learnt about the various apparatus used in the laboratory, such as the thistle funnel, measuring cylinder, etc, and also about hazard symbols such as radioactive or corrosive symbols.

Hazard symbols

Next, we learnt about the 16 Habits of Mind. One of which I was most interested in was metacognition, also known as thinking about thinking. When I heard about it, I was quite surprised that there was actually such a thing. It did not seem important. In fact, it seemed as though it was a complicated process which did not have any use. However, I read that metacognition plays a critical role in successful learning and has been linked with intelligence; it has been shown that those with greater metacognitive abilities tend to be more successful thinkers. Also, I read that metacognition involves identifying the task at which one is currently working on, checking on current progress of that task, evaluating the progress, and predicting the outcome. Only then did I realise that this is very similar to performing an experiment in science; making a hypothesis, planning an investigation, making an observation, making a conclusion, etc. This is probably why metacognition is important in science.

Metacognition

Also, we learnt about measurements. We learnt to use the vernier calipers, micrometer screw gauge. We learnt to avoid parallax errors by positioning our eye vertical or perpendicular to the mark which we want to read. There is also the meniscus reading in liquids, where we have to read the bottom of the liquid level if it is a concave meniscus, and we have to read the top of the liquid level if it is a convex meniscus. This is one way to improve accuracy. It was interesting to use more accurate instruments such as vernier calipers and micrometer screw gauges which have an accuracy of 0.01cm. Conversion was also an important factor in measurements. 

Vernier caliper

For this term's test, I scored a 68 (B3). I did quite well and was pleased with myself for doing so, but felt that I definitely could have achieved an A2. My mistakes were particularly at the MCQ section and I made some careless mistakes too. I hope to be able to score better next term!

Introduction

Welcome to my science e-portfolio! I am Yeong Yu from 1P2 (31). Through this blog, I will be sharing my termly reflections and summaries, favourite practical experiments, etc. :)