Control Group
Why do we use a control group?
The control group provides your baseline, and you do not change your control group in an experiment.
What is an observation?
In science, an observation is any information gathered using our senses (seeing, hearing, smelling, tasting, or touching) or through scientific instruments that extend our senses (like telescopes, microscopes, etc)
What is a variable in science?
Variables are any factors that can be controlled, changed or measured in an experiment.
Which of these temperature changes causes a chemical change?
A. water drops forming on a cold can
B. A wet beach towel drying in the sun
C. melting chocolate on a stove
D. baking cookies in an oven
D. baking cookies in an oven
What is a physical change in matter?
A physical change is a change in the state of a substance without altering its chemical composition.
For this experiment, Matthew will be experimenting with butterflies and whether they see color.
What should be his control group for this experiment?
1. Different species of butterflies
2. Red flowers
3. Yellow flowers
4. No flowers
4. No flowers
What is a hypothesis?
A proposed idea that can be tested through research and experimentation.
What is the constant variable?
The constant variable in an experiment is what is the same for all the groups.
What happens to the particles of a substance during a chemical change?
During a chemical change, the particles (atoms and molecules) of a substance are rearranged, and new substances with different properties are formed.
What is it called when the particles of a solid gain energy and the substance becomes a liquid?
A. freezing
B. melting
C. boiling
D. evaporation
B. melting
What is the meaning of a control group?
A control group is the group that you don’t change any part of the experiment.
When do you collect data in an experiment?
Step 3: After you conduct an experiment to test the hypothesis.
What is the independent variable in an experiment?
So the independent variable is the one thing in the experiment that you plan to change.
Which of these choices describes an increase in temperature causing a chemical change?
A. Water boiling in the kettle
B. Onions turning brown in a skillet
C. A carrot being chopped into pieces
D. A popsicle melting on a counter
B. Onions turning brown in a skillet
Three vegetables are chopped into smaller pieces and combined in a bowl to make a salad. Is this a chemical change or a physical change?
A physical change.
Controlled experiments will have two groups. What are they?
The control group and the experimental group.
1. Make observations. 2. Develop a hypothesis. 3. Design and conduct an experiment to test the hypothesis. 4. Collect data. 5. Evaluate the results of the experiment. 6. Accept or reject the hypothesis. 7. If needed, make and test a new hypothesis.
What sre the steps of an experiment?
What is the dependent variable in an experiment?
The dependent variable results are “dependent” on the independent variable. We can remember the dependent variable as the “responding variable” and is what you will measure during the experiment.
Define the term chemical reaction in your own words.
Answers may vary. Possible answer-
"A process where one or more substances (reactants) are transformed into new substances (products) with different properties."
How does the mass of a melted ice cube compare to the mass of the solid ice cube?
The mass of a melted ice cube is the same as the mass of the solid ice cube. This is because the ice is simply changing its state from solid to liquid, but the total amount of matter (water molecules) remains constant, says the law of conservation of mass.
What is Reliable data in a controlled experiment?
Something that has not been changed in an experiment.
What is the last step of the Scientific Method?
Once your experiment is complete, you collect your measurements and analyze them to see if they support your hypothesis or not.
The conditions are the same for all groups in the experiment.
What is the Constant Variable?
A student places water on a fresh slice of bread and seals the wet bread in a bag. Then the student places the bag of wet bread on a balance, and the balance reads 20 grams. After 10 days, the student observes mold growing on the bread and inside the bag.
Is this a chemical change?
Yes, the growth of mold on bread is a chemical change.
What is an example of a physical change in matter?
A student removes a loaf of bread hot from the oven. The student cuts a slice off the loaf and spreads butter on it.
Answers may vary.