Observation Investigatiohns

If you have read detective or mystery stories or watched them on TV, you will know that many crimes are solved because somebody has made careful observations. Perhaps the finding of a fingerprint, the smell of petrol, an unusually sour drink, a strange sound or a speck of blood on the carpet has helped to track down the guilty person.

An observation is something that you can see or find out using your senses. For example, you can observe that a pile of decomposing rubbish smells, that tūi sing at sunrise or that a green apple tastes sour.

Imagine you are 5 years old, standing at the side of the road waiting to cross. You observe the cars to know when it is safe to cross. When you first try and cross the road you find it difficult, but as you grow older you gain more experience and are able to do more than just look, you can determine how fast the cars are going, if they are slowing down or speeding, if the are indicating to turn or if they have waved at you to cross. You also get advice from your parents and older siblings on how to cross the road safely. We can use this analogy in Science investigations - where we use observations and knowledge gained from those many observations to get a better understanding of something.

Observations are important in Science as they are often a starting point for further questions and provide information in investigations

There are two types of observations:

• • Qualitative observations are descriptive - they describe a quality of something. They can be written in words or as labelled diagrams. For example a person could describe the sun as being bright, a box as being heavy or as feeling tired. There are no numbers or measurements used in qualitative data. Qualitative data is important when things can’t be measured. For example a school might want to know how students feel about homework, no cell phones in schools or the changes from 5 subjects to 6 subjects. To help you remember: qualitative, think l for looking.

  • Quantitative observations are measurements and are written as numbers and have units - they describe a quantity of something. For example the sunlight brightness is 2670 lux, the box has a mass of 70.6 kg and a person gets an average of 6 hours and 45 minutes of sleep each night. Qualitative data is useful when you are trying to determine cause and effect, e.g. does the amount of sleep you get affect your test scores? To help you remember: quantitative, think n for numbers.

Finally, when making observations, it is important to be specific, giving details and measurements where possible.

Most investigations start with something being noticed or observed. For example, the story goes that in 1796 Edward Jenner, an English doctor, noticed that milk maids (women who milk cows) who had experienced cowpox (a skin infection caused by a virus, seen as ulcers on the udders of cows) didn’t catch smallpox (a much more serious disease caused by a virus similar to cowpox).

The observation was a starting point for the development of a smallpox vaccine, leading eventually to the eradication of smallpox.

However, Jenner could not just observe milk maids didn’t get smallpox and be sure of any link between previously cowpox infection and immunity to smallpox. The observation was a good starting point that led to many further investigations, that eventually led to the development of the smallpox vaccine.

Some observation investigations are quick to carry out and you can make many observations at one time. They can also lead to more questions and therefore more investigations.

However, some observations are very time consuming and may involve a lot of standing around and waiting. This can cause you to become unmotivated and disinterested.

Observations often, but not always, lead to qualitative observations rather than quantitative ones.

However, often observations alone don’t prove anything. Other investigations like fair tests and pattern seeking can lead to more solid conclusions than observations can. We will do these types of investigations later in the topic.

A conclusion is the part of an investigation that summarises the results of what we found out. 

Since an observation investigation uses the senses to see how something changes over time, a conclusion for this would be a description of those senses (what we see, smell, hear and feel) change over time.

For example, we can observe a candle before lighting, when we light it, while it is burning and after we blow it out. So our conclusion of this observation investigation would be a detailed description of what we see, smell, hear and how the candle changes over time.