What makes a question testable? Essential Question  What makes a question testable? How do we find answers with scientifically reliable methods?

The Scientific Method & Experimental Design

In science, we only deal with facts From observations From experiments

The scientific method is a systematic way to help us find answers to the questions we have There are 5 main steps

Observation and Research Step 1 Observation and Research See Hear Smell Taste Feel For example: I got home from school and I smelled gas when I walked in my house.

Step 1, continued Observations lead to questions For example: Why does it smell like gas in my house?

Step 2 Form a hypothesis a statement that predicts a relationship between cause and effect A good hypothesis will follow the “if…then” format Example: If I smell gas, then there is a gas leak.

Step 2, continued A hypothesis must be testable. For example: I can collect data (do a test) to see if there is a gas leak. But if I said, If I wear perfume, then I will smell good I can’t test that

Step 3 Gather data/experiment You can do this by designing an experiment, making more observations, taking measurements, etc.

Step 4 Data Analysis Look at the facts you collected and see if they mean anything or give you any answers. This is one of the most important steps!

Step 5 Conclusion – Do you accept your hypothesis or reject it? If your data supports the hypothesis, you accept it If your data does not support it (even a tiny bit), you reject it and start over

Let’s try it Step 1 Observation The light doesn’t come on when I flip the switch. That leads to a question: Why?

Step 2 Hypothesis Use the “if…then” formula If the light doesn’t come on, then The bulb is burned out The lamp is unplugged The power is out Finish the hypothesis on your paper

What experiment or data would you do or gather? Step 3 - Experiment You can check the bulb or the plug, try other switches in the house, etc. You are gathering data to help you answer your question. What experiment or data would you do or gather?

Step 4 Analyze Data Look at the facts you gathered to see if they support your hypothesis or not Let’s say your hypothesis was that the power was out and you found that none of the switches worked. That would support your hypothesis

Step 5 Conclusion Accept the hypothesis But if you found that the other switches did work, reject the hypothesis and make a new one

Experimental Design When scientists design experiments, they must follow certain rules. A good experimental design has: One independent variable A dependent variable A control group

Experiments The independent variable is the thing you change in the experiment

Experiments The dependent variable is the thing you measure during the experiment

Experiments The control group is for comparison You do not experiment on the control group

Let’s practice – first watch me So what is the INDEPENDENT VARIABLE? (the one thing that is different?) So what is the DEPENDENT VARIABLE? (the thing that is being measured?) Samantha wanted to know if fish breathe faster in warm water. She set up three tanks: 1 with fish in cold water (10 degrees C) 1 with fish in room temperature water (20 degrees C) 1 with fish in warm water (30 degrees C) Then she counted how many breathes they took for 1 minute The one with normal (room temperature) water The number of breaths The temperature of the water Which tank is the control tank?

Let’s practice What will be my independent variable? The type of fertilizer What will be my dependent variable? The number of strawberries on each plant. What will be my control group? Strawberry plants with no fertilizer I want to know what kind of fertilizer will make me get the most strawberries on my plants. Remember: Independent Variable is what I control Remember: Dependent is what I am looking for Remember: the control group does not get the independent variable

Data Data collected is of 2 types: Quantitative- numbers, measurements, etc. temperature, length, mass, etc. Qualitative – non-number data that cannot be expressed as a number Shapes, colors, smells, etc.

Data practice... What kind of data would I have collected in my strawberry experiment? Quantitative Why? Because I was counting the number of strawberries

Scientific Errors Poor measuring techniques Researcher bias Poor experimental design Same person should do all measuring, same machine used throughout, etc.