Science facts: How science works and works scientifically

 

Science is the key to understanding the world. Scientists come up with theories and test them with experiments to help us answer all kinds of questions from how living things survive to why planes don’t just fall to the ground. Engineers use science and math to invent new technologies that make our lives easier.

 

How is science works

Science is more than just a collection of facts. It’s also a way of discovering new facts by having ideas and then testing them with experiments.

 

The scientific method

Most scientists carry out experiments to test their ideas. An experiment is just one step in a sequence of steps that form what’s known as the scientific method. This is how it works.

 

 

1. Make an observation

The first step is to notice, or observe, an interesting pattern. For instance, you might notice that the grass growing in old cow pies is taller and greener than the grass elsewhere.

 

 

2. Form a hypothesis

The next step is to form a scientific idea that explains the pattern. This idea is called a hypothesis. You might think, for example, that something in cow pies helps plants grow taller.

 

3. Carry out an experiment

 

Next you test your hypothesis by carrying out an experiment. In this case, you might grow plants in three types of soil: soil with lots of cow manure; soil with a little cow manure; and soil with none. To improve your experiment, you might grow lots of plants in each type of soil, not just one of each.

 

4. Collect data

Scientists collect results (called data) from experiments very carefully, often using measuring instruments such as rulers, thermometers, or weighing scales. To compare how well different plants grow, you might measure their height with a ruler.

 

5. Analyse results

To make the results easier to understand, you might plot them on a graph. The graph here shows the average height plants grew to in the different kinds of soil. Growing lots of plants and working out an average for each type of soil makes the results more reliable. In this case, the results support the hypothesis that manure helps plants grow.

 

6. Repeat the experiment

A single experiment doesn’t prove a hypothesis is true—it just provides evidence that it might be true. Scientists usually share their results so that others can repeat the experiment. After many successful results, a hypothesis may eventually be accepted as a fact.

 

Working scientifically

Working scientifically means working in a careful and methodical way that makes errors less likely to happen. Scientists take great care to avoid errors when they carry out experiments.

 

Taking measurements

Many experiments involve measuring things. For instance, in a chemistry experiment you might measure a liquid’s temperature. To be confident of getting the right answer, it would be wise to measure the temperature several times, but this could give you several different readings.

 

1. Precise but not accurate

 

Imagine you take the temperature four times and all four readings show the same number to two decimal places, but the thermometer is faulty. The readings are precise but not accurate.

 

2. Accurate but not precise

Now imagine you use a different thermometer that isn’t faulty but the readings are all slightly different perhaps the tip of the thermometer was in a different place each time. The readings are accurate but they aren’t precise.

 

3. Accurate and precise

Finally you stir the liquid before taking the temperature, and all four readings are about the same and all correct. They are accurate and precise. Whenever scientists take measurements, they try to be accurate and precise.

 

Bias

Scientists also strive to avoid something called “bias,” which causes errors to creep into measurements. For instance, imagine you use a stopwatch to time how long a chemical reaction takes. The stopwatch might be perfectly accurate and precise, but because it takes you half a second to press the button, all your readings are incorrect by the same amount.

 

Working with variables

The most important things a scientist measures during an experiment are called variables. There are three important types of variables: independent, dependent, and control.

 

Independent variable

This is something a scientist deliberately changes as part of an experiment. In an experiment to see if salt dissolves faster in hot or cold water, you might use two beakers of water, one hot and one cold. The water’s temperature is the independent variable.

 

Dependent variable

This is the variable you measure to get your results. In the salt test, for instance, the dependent variable is the time salt takes to dissolve. It’s called dependent because it might depend on another variable, such as how hot the water is.

 

Control variables

These are variables you keep carefully controlled so they don’t harm an experiment. In the salt test, they include the amount of salt and the amount of water. These must be kept constant in both beakers so they don’t affect the dependent variable.

 

 

Working together

Teamwork is important in science. All scientists build on the work of earlier scientists, either strengthening their ideas with new evidence or overturning theories altogether. Scientists work in groups to pool their skills and expertise, and they share findings by publishing them. But different teams also compete to be the first to carry out a successful experiment.