SCIENCE FAIR MiniLesson 4 Identifying Variables Writing a
SCIENCE FAIR Mini-Lesson #4 Identifying Variables, Writing a Hypothesis, Listing Materials & Outlining the Procedure
Let’s Begin…… On your desk you have some questions to answer. Read “Variables In a Science Fair Project, ” “Hypothesis, ” “Materials” and “Experimental Procedure” in the blue folder and answer the questions. You will have 30 minutes to find all of the answers. Remember: DO NOT WRITE IN OR ON THE BLUE FOLDER!
Let’s Answer Those Questions… 1. What is a variable and what are the 3 variables found in any experiment? • Any factor, trait, or condition that can exist in differing amounts or types. In any experiment there exists the independent variable, the dependent variable and controlled variables 2. How many variables should a scientist change in a good experiment? • One
3. Contrast independent variables and dependent variables • An independent variable is what the scientist changes but a dependent variable is what a scientist is measuring 4. What is the purpose of a control variable? • Conditions that a scientist wants to keep constant so they cannot affect the outcome of the experiment
5. What is a hypothesis? • An educated “guess” about how things work 6. Why did you write your research paper first? • To give you background knowledge to make a good hypothesis 7. Is it bad if your experiment disproves your hypothesis? • No, in fact very few scientist have EVER been correct on their very 1 st try.
8. What is an experimental procedure and why should it be detailed? • A step-by-step recipe for your science experiment. It should be detailed so others could replicate it and get the same results. 9. Contrast the control group and the experimental group • The experimental group are the trials where you change the independent variable. The control group are the trials where the independent variable is left in its’ natural state and basis of comparison (what is normal. )
10. Explain why some experiments will not have a control group. • Some experiments have independent variables that do not have a natural/normal state 11. Explain why it is important to have a very detailed materials list before you perform your experiment. • To make sure you have everything on hand when you need it.
PRACTICE SCENARIO: A student would like to test the effect of varying the amount of water on the growth of red roses. To test this, a student grew 3 identical types of red roses in 2000 m. L plastic buckets. One with a normal, recommended amount (50 m. L) of water, one rose given twice as much water as normal and one rose given three times the recommended amount of water. They were given the same amount of sunlight and type of tap water. The plants were also given 60 g of Miracle. Gro Plant food 1 x/week. Every day the overall height of each plant was checked and recorded.
a. What is the independent variable? • amounts of water b. What is the dependent variable? • rose plant growth c. Why were all other variables kept the same? • To make sure only water caused the plant growth.
d. After writing a research paper, the student in the above scenario found out that more water will lead to an increase of rose growth, write an appropriate hypothesis for the student. You must write this as an if/then statement – the IF part is followed by the independent variable, the THEN part is the dependent variable PLUS THE PREDICTED OUTCOME based on RESEARCH. • If more water than normal is added to the rose plant, then the rose plant will grow more than normal. ** NOTICE NO I’s in the written hypothesis!!!**
e. Which plant(s) would be considered the control group? • Those grown with a normal amount of water f. Which plant(s) would be considered the experimental group? • Those grown with a non-normal amount of water
g. Sort the pattern puzzle into the appropriate steps for the experimental procedure. Once you have sorted the steps, write down what was included in the procedure that you should also include in yours. - A step-by-step list of everything that must be done in the experiment. Within that recipe there should be: • Identification of the independent and dependent variables and how they will be changed/measure • Identification of experimental and control (if applicable) groups
• What the controlled variables are and how they will be maintained • How many times the experiment will be repeated (plants need 1 x – sports/short p. H experiments need multiple test to ensure accuracy)
STEP 1: Three red rose plants of the same species were planted in the same 2000 m. L Container. STEP 2: The first red rose plant is considered the control group and given the recommended 50 m. L of water every day for 4 weeks.
STEP 3: The second and thirds rose plants are the experimental groups. The amount of water in these rose plants will be varied as the independent variable. Therefore, the second rose plant is given 100 m. L of water every day for 4 weeks and the third rose plant is given 150 m. L of water every day for 4 weeks. STEP 4: The dependent variable is the amount of rose plant growth. This will be measured in centimeters using a ruler everyday of the 4 weeks.
STEP 5: To control all other conditions, the plant’s growth will be measured every day at 3 pm. Water will be given to each plant at 7 am every day. The water will be of the same type – tap water. Each plant will be exposed to the same amount of light from 7 am to 7 pm using sunlight. Each plant will be given 60 g of Miracle. Gro plant food on the first day of every week at 3 pm.
h. Write a DETAILED materials list including amounts of item is SI units that were used 1. 3 -red rose plants 2. 3 - 2000 m. L buckets of the same shape, color, etc. 3. 720 g of Miracle. Gro plant food 4. ruler 5. tap water readily available for 4 weeks 6. sunlight 7. measuring cup (in milliliters) 8. scale (used to measure milligrams) 9. pen 10. lab notebook
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