Unit 0: Good Scientific Practices

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Unit 0: Good Scientific Practices

Basic Intro video

This is arguably the most important unit in the entire course. Here, you will learn how to make a proper experiment, learn the different types of variables, and learn how to make a properly formatted lab report.

Key Terminology:

Observation: Something measured with the 5 senses (qualitative) or measured and assigned a value (quantitative). This is a factual statement. An example of a qualitative observation is: This rock is very hard. An example of a quantitative observation is: There is 5ml of water in this dropper.

Inference: An explanation for an observation, an intuitive educated guess, mostly opinion based. Inferences are not necessarily true. An example of an inference is: This substance is a good conductor because it's a metal.

Variable: A singular quantity/value which can be changed in an experiment. For example in an experiment about how the intensity of light on a lamp takes up power, both the light intensity and the power used (voltage) (see Current Electricity sub-unit) are variables, because they change.

Independent Variable: Variable which is to be changed in the experiment. For example, in an experiment about how water temperature affects plant growth, the water temperature would be the only variable that can be altered, so it would be the independent variable. In a graph, the independent variable always takes the x-axis.

Dependent Variable: Variable which is changed as a result of a change in the independent variable. For example, in the same experiment mentioned before, when you alter the water temperature, the plant growth changed as a result, so it would be the dependent variable. In a graph, the dependent variable always takes the y-axis.

Control Variable(s): In the vast majority of cases in a scientific experiment, you must only change 1 (one) variable at a time (this is the independent variable), and have 1 direct result (the dependent variable). You must not use other variables in an experiment (except in certain circumstances, which do not happen in high school science), and these other variables must remain the same and be unchanged, so as to retain the data integrity (If you change two independent variables, it is hard to determine which of the two caused the dependent variable's value to change, so the data is void).

In the experiment mentioned before would be: pot size, humidity, plant species, etc. You must find as many obvious control variables as possible and make sure they are the same in all iterations of the experiment. However, be aware that many factors exist and you will likely not find all the control variables.

Hypothesis: An educated guess on what the outcome of an experiment will be, based on some limited evidence or previous knowledge, and will become the starting point for an experiment and promotes testing to prove the hypothesis true or false.

For example, in an experiment about how water temperature affects plant growth, a hypothesis could be that warmer water helps plants grow better, based on previous experience and knowledge.

Conclusion: Once you obtain a solid outcome in an experiment, a conclusion is a statement summarizing whether your hypothesis was true or false, and any other additional findings you discovered, backed up with a solid explanation.

For example, in an experiment about how water temperature affects plant growth, a conclusion could be that your hypothesis that warmer water helps plants grow better, is correct, but that overly heated water will also harm plants, based on the findings of your experiment, when you tested plant growth over a long time with certain temperature intervals for each plant.

Quantitative Data: An educated guess on what the outcome of an experiment will be, based on some limited evidence or previous knowledge, and will become the starting point for an experiment and promotes testing to prove the hypothesis true or false.

For example, in an experiment about how water temperature affects plant growth, a hypothesis could be that warmer water helps plants grow better, based on previous experience and knowledge.

Qualitative Data: Once you obtain a solid outcome in an experiment, a conclusion is a statement summarizing whether your hypothesis was true or false, and any other additional findings you discovered, backed up with a solid explanation.

For example, in an experiment about how water temperature affects plant growth, a conclusion could be that your hypothesis that warmer water helps plants grow better, is correct, but that overly heated water will also harm plants, based on the findings of your experiment, when you tested plant growth over a long time with certain temperature intervals for each plant.

How to do a Proper Experiment - Proper Experimental Design

When you think of experiment, you might think randomly mixing chemicals together, but its not really an experiment. An actual scientific experiment, which is a series of steps performed to find out an answer to a scientific question, has certain criteria to follow.

video here

It has a clear, well defined question formatted, with key question works like : (Does, How, Why, When, etc).

For example: Does water temperature affect plant growth in cm?

See how a variable is defined

It tests only one variable at a time (usually). For the reasons we mentioned when we talked about variables
It has repeated trials, or replications. This reduces the likelihood of outliers such as random chance factors, experimental errors, etc, and from the average of the replications you can draw a more accurate conclusion. Remember, just because a result occurs once doesn't mean it is the correct result, it could very well be an outlier.

For example, if you test how plants grow in plain water vs salt water, and you see how a plant grew 10cm in salt water and only 2cm in plain water, that isn't necessarily correct. For all you know you could have a data set like this:

Plant Growth in Water Types

Test Number Plain Water Salt Water

1 2cm 10cm

2 10cm 5cm

3 12cm 3cm

4 5cm 1cm

5 15cm 0cm

6 8cm 2cm

See how the data set you got compares to the first test, which is definitely an outlier?

Example Experiment:

Question: Does the type of shoe you wear affect jump height in cm?

Independent variable: Type of shoe worn

Dependent variable: Jump height in cm

Control variables: Surface of jump, Person jumping, Tiredness/energy levels of person jumping, Quality/age/wear of shoes, etc.

So in order to account for as many control variables as we can, we must have the same person jumping, on the same surface, with new quality shoes for each brand.

Remembering the principle of reiteration/repetition.

Test Results (random results)

Test No. Reebok Adidas Nike Saucony

1 45cm 55cm 39cm * 51cm

2 40cm 52cm 40cm 43cm

3 32cm 53cm 37cm 42cm

3 35cm 48cm 35cm 38cm

4 31cm 45cm 30cm 39cm

6 28cm 42cm 29cm 36cm

Notice how the jump height generally decreases as more tests are done? This means the person is getting tired, and the earlier tests are more valid than the later ones.

*Also notice that Saucony has an outlier of 51cm in the first test when all the rest average in the late 30s and early 40s

How to Make a Proper Lab Report

Making a proper lab report is a key skill for the world of science. No matter it be biology, chemistry, or physics, it's an essential skill. And there is a set of criteria you must follow,. It may vary slightly depending on the topic of the lab report, but the general template is usually followed.

in the video included below, we go over this in detail.

video here

Experiment: Testing the Law of Conservation of Mass in Open and Closed Systems is the example experiment used for the lab report.

Criteria:

General Tips:

Avoid use of personal pronouns such as I, we, me you, etc. Instead, state your findings from an objective point of view, in the passive voice. Quote your statistics whenever you can.

For example, instead of: I found that warmer water helps plants grow better, use According to the findings shown (insert reference), warmer water helps plants grow better.

Keep your formatting consistent throughout

Indent all the way from key headings: Indent after every heading, after every subheading, etc. Be reasonable about this.

Be organized, but don't be reluctant to have two or more sections share the same page if there is enough room. Don't let paragraphs and tables, etc be cut off though, if that will happen, make a new page.

There are several sections you need to add:

Title Page

Purpose/Introduction/Question

Hypothesis

Materials

Method/Procedure

Observations

Experimental Uncertainties

Analysis/Conclusion

References

Note that not all sections will need to be included in every lab report! Many of the sections will only comprise a few sentences at most.

Example report topic: Law of Conservation of Mass in Open and Closed Systems

(This topic will be used as the example

Topics you can use for a lab report: Link here

Image Carousel: Parts of a Lab Report

Example Lab Report PDF:

Here is the link to the lab report for the example topic: Testing the Law of Conservation of Mass in Open and Closed Systems

Copy of Lab Report on Law of Conservation of Mass

G.R.A.S.S / G.R.A.S.P Method

This is a very standard method of answering a question, and many teachers look for all the steps when you answer a question. So be sure to follow GRASS/GRASP and don't miss any steps. Some teachers deduct points for missing steps even if the answer is accurate. You need a system like this, because if a question is very hard, and has multiple values you need to solve for, or a complex equation, you need to keep track of your work so that you don't make errors.

Here are the five steps you must follow below:

Given: What values do you have.

Required: What values do you need

Analyze: Steps you take to reach the solution

Solution: What is our solution

Statement/Paraphrase: A sentence to describe the solution and paraphrase the question, insert the solution.

Example Problem:

For the purposes of demonstration we will use an equation (that we will get to later) called Ohm's Law, which is V = I x R (or Voltage = Current x Resistance).

The problem is. For a device which has a potential difference of 240V, and has a current of 40A, what is the resistance?

So we will use the GRASS method.

First, what values are we provided? (Given)

We are given the potential difference, which is the V value, and the current, which is the I value.

So we know that V = 240 V and I = 40A

Secondly, what values do we need? (Required)

We need the R value of the equation, which is the resistance in Ohms (Ω).

Thirdly, we need to use this information to find the answer (Analyze)

So we have the equation: V = I x R. So we need to use algebraic inversion to find the R value. R = V / I

V = I x R

240V = 40A x R

R = 240V / 40A

Solution: R = 6 Ω

Statement: The device has a resistance of 6 Ω

And that's how to use GRASS

If you wanted a video version, click on the link here: (coming soon)

Unlike other units, the unit test is a google form. seeing as you aren't formally tested on this unit, technically. But you still need to know this unit. So this is a google form

(below)

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Unit 0: Good Scientific Practices