Scientific Method & Experimental Design

Transcription

1 Scientific Method & Experimental Design Objectives: 1. Understand the purpose of the scientific method 2. Be able to create a hypothesis from a problem or question 3. Design a controlled experiment 4. Identify dependent and independent variables 5. Understand the purpose of data tables and graphs 6. Know how to improve the accuracy of an experiment Key Vocabulary: Scientific Method Hypothesis Controlled Experiment Control Group Experimental Group Independent Variable Dependent Variable Constants Theory Let s see what you know! Create an experiment to figure this out: You want your tomato plants to grow more tomatoes than your neighbor (what a showoff). You go to the store and see good looking fertilizer called Joe s Fertilizer. You ask yourself, Will Joe s Fertilizer make my tomato plant grow more tomatoes? Controlled Experiment What do you need for a valid scientific experiment? 1

2 Creating a Hypothesis Smithers thinks that a special juice will increase the productivity of workers (cut more paper). He asks himself, will this special juice increase my workers productivity? What would be a good hypothesis? Johnson wonders if radio waves will make his mouse stronger for a race coming up. He asks himself, will radio waves make the mouse faster? What would a good hypothesis be? What would be a good hypothesis? Creating a Hypothesis Hypothesis Is a or as to what will happen Use your question to create a specific hypothesis Hypothesis **** ALWAYS (what might happen) ALWAYS and! In other words, stated as: IF, THEN will happen. A hypothesis serves as a basis for determining what data to collect when designing an experiment. HYPOTHESIS PRACTICE (Back) Creating a Controlled Experiment Controlled Experiment Terms: 1. An experiment where only thing, is changed to see if it has any effect 2

3 2. The group that receives the thing being tested ( ) 3. The This group is the to see if the independent variable in the experimental group had any effect Everything is the same as the experimental group except one thing (independent variable) 4. Independent variable 5. Dependent variable 6. Constants Factors that remain the same for both groups (the experimental and control groups) Controlled Experiment What is needed for a good experiment? sample size (amount of ) trials A or comparison group Only thing, variable, is changed! What can be done to make an experiment more accurate or reliable (valid)? the amount of test subjects the experiment 3

4 Design and carry out a controlled experiment This is a test or a series of tests to see if your hypothesis is right or wrong. Smithers thinks that a special juice will increase the productivity of workers (cut more paper). He asks himself, Will this special juice increase my workers productivity? What would be a good hypothesis & experiment? Create a Hypothesis & Design a Controlled Experiment Identify the control and experimental group(s). 1. Everyone uses a Duracell battery, but does a Duracell battery last longer than an Energizer battery? 4

5 2. I usually use white light for my plants. I want to know if using green light would help my plants grow taller. Observation and Data Collection Graphs and Data tables? Make observations using tools (rulers, stop watch etc ) Take data and organize into a table or graph Purpose: Graphs are used to and see the results more clear Carrots: Conclusion Conclusion See if your conclusion supports or refutes your hypothesis (see if your hypothesis is right or wrong) If right or wrong, In a laboratory, spinach leaves exposed to continuous fluorescent light increased in vitamin content by 50 to 100 percent. Spinach leaves kept in darkness for a similar period of time either lost vitamin content or produced no gain. Describe how these findings could influence the way in which spinach is displayed for sale in supermarkets. What s your conclusion? 5

6 Repeat!! Repeat Repeat or redesign the experiment and share with others! Why might it be important to repeat and experiment? Why might it be important to share scientific knowledge? So scientists can from one another The scientific body of knowledge faster To faster So other scientists can your experiment and see if it s right or wrong. Increased accuracy!! Theory An explanation, supported by many experiments and lots of evidence that can be used to accurately explain related occurrences. Strong Theories Heliocentric Theory, Plate Tectonics Theory, Evolution, Cell Theory DO NOW SPACE 6