Scientific Method and Conversion Factors (1ESO English)

​Scientific Method

What is the Scientific Method?

The scientific method describes the steps we follow when we do science. This method is divided into several steps, each of which has a particular meaning and goal. It's important to understand them all in order to do experiments correctly.

Once we have observed something we want to study, the following step is to create a hypothesis: that is a theory that ​might explain what we observed. In the previous example, a hypothesis might be that I feel tired because I don't sleep enough.

2) Creation of a hypotheses

All scientific investigations start with the observation of a certain situation that we want to study. For example, I might observe that I'm really tired each day when I arrive to the high school.

​1) Observation of a situation

​Steps of the scientific method

4) PERFORMING THE EXPERIMENT

Once designed, we have to actually perform the experiment. We have to be really careful when doing it, and we have to make sure we record all the data we gather, so that we can analyze it later.

In order to test our hypothesis and see if it is correct, we have to design an experiment. This is often hard, but if the experiment is well designed, it will help a lot in clarifying whether our hypothesis is true or false.

3) designing an experiment

​steps of the scientific method

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Once the data from the experiment is analyzed, we are in a position to either accept or reject our initial hypothesis: if the data matches our hypothesis, we will accept it; else we will reject it.

6) ACCEPTING/REJECTING THE HYPOTHESIS

Once the experiment is finished, we must analyze the data we obtained from it. This requires drawing graphs, making calculations... in order to see if there are patterns that relate to our hypothesis.

5) ANALYZING THE DATA

​steps of the scientific method

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We must finally share our results with the rest of the scientific community, so that other people can replicate our experiment or propose interesting variations to it. Since our work will be read by a lot of different people, it is important that we write our findings as nicely as possible and that we explain very carefully each step we took during the experiment. Remember: others must be able to exactly replicate your experiment, so be very precise when explaining how you performed it!

7) sharing our findings

​steps of the scientific method

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Multiple Choice

What is a hypotheses?

• A supposition we make at the beginning of the Scientific Method

• A piece of knowledge we obtain at the end of the Scientific Method

• The result of a scientific experiment

• An absolute truth that we can prove by using the Scientific Method

Multiple Choice

When using the Scientific Method, which of these should we trust ?

• The result of the experiment

• Our hypotheses

• The most popular opinion

Multiple Select

The experiment we design during the Scientific Method...

• must be rigorous and detailed

• must be replicable

• is of no utility if its result contradicts our hypotheses

• includes measuring different magnitudes

Multiple Choice

What must be done before creating a hypotheses?

• Observing a phenomenon or a problem

• Performing an experiment

• Extracting conclusions from our experiment

• Designing an experiment

Multiple Choice

What must be done if the results of our experiment contradict our hypotheses?

• Alter the experimental results so that they coincide with the hypotheses

• Repeat the experiment until we get the results we expected

• Conclude that our hypotheses can not be proved

• Rethink the hypotheses and change it

Multiple Choice

I'm studying the number of goals a team scores over a season.

I think that the number of goals scored depends on the number of attacking players this team has.

What am I doing here?

• Observing a problem

• Proposing a hypotheses

• Performing an experiment

• Analyzing the results of an experiment

Multiple Choice

I'm studying the number of goals a team scores over a season

I decide to make calculations using data from each team's past season.

What am I doing here?

• Observing a problem

• Proposing a hypotheses

• Performing an experiment

• Analyzing the results

Multiple Choice

I'm studying the number of goals a team scores over a season.

I notice that some players score a lot of goals, while others don't score a single goal.

What am I doing here?

• Observing a problem

• Proposing a hypotheses

• Performing an experiment

• Analyzing some results

Multiple Choice

I'm studying the number of goals a team scores over a season.

I ask different players to take turns shooting and count how many goals each player scores.

What am I doing here?

• Observing a problem

• Proposing a hypotheses

• Performing an experiment

• Analyzing some results

Multiple Choice

I have a certain hypotheses, I perform a single experiment and the results agree with the hypotheses. Can I conclude that the hypotheses is correct?

• Yes, because the experiment confirmed it

• Not yet, the experiment must first be replicated by other scientists to see if they get the same results as I do

• No, because a hypotheses can't be confirmed with an experiment

• Yes, because the hypotheses is always true

A unit is a known value that we compare our measurements to. For example, a second is a known amount of time, and we use it to understand how long or short an interval of time is.

What is a unit?

A magnitude is something which can be measured. Examples of magnitudes include the mass, the distance, the time, the temperature, the force... all of these can be measured using different devices.

What is a magnitude?

​Magnitude vs. Unit

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Multiple Select

Which of these are magnitudes?

• Time

• Seconds

• Distance

• Kilometers

• Temperature

Multiple Select

Which of these are units?

• Liters

• Seconds

• Distance

• Kilometers

• Temperature

In Science we use different units to express different magnitudes (mass, time, distance, ...). In order to change from one unit to another one, we use Conversion Factors. Here we will learn how to do them and we will do a few exercises to practice them.

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Conversion Factors​

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​First, we must get familiar with the Greek prefixes we use to name different units. These prefixes make a certain unit bigger or smaller, each time by a factor of 10. This means, for example, that 1 kilo is equal to 10 hecto; 1 hecto is equal to 10 deka; 1 deci is equal to 10 centi, and so on. Therefore, each "jump" requires multiplying or dividing by 10; if we have to do 4 jumps, we will need to multiply or divide by 10x10x10x10=10000.

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We usually use capital letters for larger prefixes (Kilo, Hecto, Deka) and small letters for smaller prefixes (deci, centi, mili).​

​How to do a Conversion Factor (I)

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​We must now fill in this conversion factor. In order to do this, we have to write the unit we want to eliminate (the km in this example) in the bottom of the fraction, and the unit we want to keep (the meters in this case) in the top. We must finally fill out some numbers: we always start by writing a 1 next to the largest unit (the km in this example). Then, we need to look at the list of prefixes that we saw in the last slide and count the number of jumps needed to go from the largest to the smallest unit. In this case, going from km to m requires 3 steps. This means we have to write 10x10x10=1000 next to the m.

​How to do a Conversion Factor (II)

Finally, we must calculate the final value. To do this, we just need to perform the operations that the conversion factor tells us:​

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​This means that 56 km is equal to 56000 m, and the conversion factor is finished!

Multiple Choice

Which unit is larger?

• Km

• m

• mm

• Hm

• cm

Multiple Choice

Which unit is larger?

• Dg

• dg

• cg

• g

• mg

Multiple Choice

If I want to convert Hm to cm, by how much must I multiply?

• $$10000$$  

• $$1000$$  

• $$100$$  

• $$10$$  

• $$100000$$  

Fill in the Blanks

Convert 32 km to m

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Convert 320 cL to dL

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Convert 2000 mg to g

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Convert 32 dL to mL