Scientific Method Chapter 1-1

What is Science?  Science – organized way of gathering and analyzing evidence about the natural world  Described as a ‘way of knowing’

Goals of Science  Provide explanations for natural events in our world  Understand patterns in nature and make predictions based on our knowledge  Predicting weather based on knowledge of atmosphere  Predict a child’s traits based on knowledge of genetics

Science is ever-changing..  As we learn more, old ideas change and new developments are made  We don’t know everything about the world, and never will  Nothing is ever proven

The Scientific Method  Organized process of answering a scientific question or solving a problem  Five steps involved

1. Observing and asking questions Notice and describe events around you Ask questions about what you are observing Why is something happening? What process is occurring?

2. Form a hypothesis Based on observations and previous knowledge, try to develop an answer to your question Hypothesis – scientific explanation for a set of observations that can be tested

3. Design a controlled experiment  Conduct an experiment that will test the hypothesis under conditions that you can control Variables – part of an experiment that changes and affects the subject of the experiment Only 1 variable is tested at a time, to observe its affects during the experiment Independent Variable – variable that you choose to change Dependent variable – factor that changes in response to the independent variable The effect

Two groups involved in an experiment: 1. Control group – group that is not affected by the variable, used for comparison 2. Experimental group – group that involves the variable Control group and experimental groups involve same exact conditions except for the one variable Comparing control group and experimental group allows you to determine the effect of the variable

4. Collect and Analyze Data Collect information during the experiment, called Data Quantitative data – numerical, such as distance, mass, temperature, population Qualitative data - observed characteristics and descriptions

5. Draw Conclusions Use collected data to determine if the hypothesis answers the question (hypothesis is supported) OR if your hypothesis does not answer the question (hypothesis is rejected)

Scientific Theories and Laws Theory – A well-tested explanation of several related hypotheses and observations, that allow scientists to make accurate predictions about new situations Developed after several hypotheses have been supported by experimentation Law – Statement that describes an observed natural event. Does not explain.

EXAMPLE Let’s go through a simple experiment: You’re observing a plant, and you think about what it needs to grow: Sunlight Water Soil (nutrients)

1.While observing the plant, you ask a question: - How does water affect how a plant grows? 2.Based on what you already know about plants, you develop a hypothesis: If a plant receives water, it will grow more than a plant that does not receive water. or If a plant does not receive water, it will grow less than a plant that receives water.

3. It’s now time to test your hypothesis by performing an experiment: First, you must determine the one variable that you will be testing: Water (Original Question: how does water affect plant growth?) Then, you must set up two groups: 1. The Control group: Will not receive variable 2. The Experimental group: will receive variable All conditions for the two groups are EXACTLY the same, except for the variable (water.) Such as type and size plant, type of soil, amount of sunlight, any fertilizers, etc.

What is the independent variable? (the part of the experiment that you choose to change) Water! What is the dependent variable? (the part of the experiment that changes in response to the independent variable) The height of the plant

4. Once the experiment begins, you must collect data to compare the two groups. What will you measure to compare the growth of the two groups? Plant Height (in cm) Over a certain period of time, you will measure the heights of the plants and record the data After the experiment is complete, you will analyze the data.

PlantWeek 1Week 2Week 3Week 4Week 5 Plant with Water 5 cm8 cm11 cm15 cm17 cm Plant Without Water 5 cm6 cm6.5 cm6.8 cm7 cm 5. After analyzing your collected data, you will draw conclusion about your experiment: Did it agree with your hypothesis? Yes: Your hypothesis is supported No: Your hypothesis is rejected

After the experiment, what should you do? If you hypothesis was supported: Try it again to confirm your results If your hypothesis was rejected: Based on what you observed, create a different hypothesis Create another experiment to test your new hypothesis