What tools are needed for a successful science investigation?
Summary
Triple beam balances are named for the three beams that each hold a weight. You place an object on the pan and it becomes unbalanced. You manipulate the weights on the three (triple) beams to achieve balance by making a small line line up with the number zero. Once you have balanced the machine, you add all three numbers together to find the mass of the object.
Graduated cylinders are used to find both the volume of a liquid, often to the nearest milliliter, and to find the volume of an irregular shaped object such as a marble or rock. You can calculate how much the water lever changed before and after the object was placed in the water to find out how much the water was displaced. This number is the volume of the object.
Pipettes are used to deliver a minimal amount of a substance. They can provide quantities that are a fraction of a milliliter in an experiment. They can also be used to draw liquid away from an object.
Beakers and flasks are similar. They are both used for storage in an experiment, but flasks have a narrow neck which can be corked or stopped with a rubber stopper. Test tubes can also be stopped with a cork. They are used for performing lots of tests on small amounts. The design of a test tube also allows for it to be put into a centrifuge.
Vocabulary
graduated cylinder: a free standing cylinder used to measure liquids; also used to measure the volume of irregular shaped objects
triple beam balance: a balance that used 3 weights spread across 3 beams to determine mass; uses grams
pipette: a small, dropper-like, tool used to distribute small amounts of liquids
Triple beam balances are named for the three beams that each hold a weight. You place an object on the pan and it becomes unbalanced. You manipulate the weights on the three (triple) beams to achieve balance by making a small line line up with the number zero. Once you have balanced the machine, you add all three numbers together to find the mass of the object.
Graduated cylinders are used to find both the volume of a liquid, often to the nearest milliliter, and to find the volume of an irregular shaped object such as a marble or rock. You can calculate how much the water lever changed before and after the object was placed in the water to find out how much the water was displaced. This number is the volume of the object.
Pipettes are used to deliver a minimal amount of a substance. They can provide quantities that are a fraction of a milliliter in an experiment. They can also be used to draw liquid away from an object.
Beakers and flasks are similar. They are both used for storage in an experiment, but flasks have a narrow neck which can be corked or stopped with a rubber stopper. Test tubes can also be stopped with a cork. They are used for performing lots of tests on small amounts. The design of a test tube also allows for it to be put into a centrifuge.
Vocabulary
graduated cylinder: a free standing cylinder used to measure liquids; also used to measure the volume of irregular shaped objects
triple beam balance: a balance that used 3 weights spread across 3 beams to determine mass; uses grams
pipette: a small, dropper-like, tool used to distribute small amounts of liquids
Why must a controlled experiment have only one independent variable?
Summary
If you want to find the effects of dog food brands on your dog's digestive system, you might alter the brand of food each week and serve him one brand per week for one month then compare what you observed as the experiment progressed. Each time give him 1 cup of dry food at 5 PM. The independent variable would be the type of food given to the dog. The dependent variable would be the digestive results (how was his bowel movement). The constants would be the amount of food you gave the dog as well as the time of day you gave it to the dog.
Vocabulary
independent variable: a variable that a scientist purposefully alters in an experiment to see its effects
dependent variable: a variable that occurs as a result of the independent variable
constants/(controlled variables): all the components of an experiment that the experimenter keeps equal throughout the experiment
controlled experiment: an experiment where one of the test objects is left unaltered
If you want to find the effects of dog food brands on your dog's digestive system, you might alter the brand of food each week and serve him one brand per week for one month then compare what you observed as the experiment progressed. Each time give him 1 cup of dry food at 5 PM. The independent variable would be the type of food given to the dog. The dependent variable would be the digestive results (how was his bowel movement). The constants would be the amount of food you gave the dog as well as the time of day you gave it to the dog.
Vocabulary
independent variable: a variable that a scientist purposefully alters in an experiment to see its effects
dependent variable: a variable that occurs as a result of the independent variable
constants/(controlled variables): all the components of an experiment that the experimenter keeps equal throughout the experiment
controlled experiment: an experiment where one of the test objects is left unaltered
How can data interpretation lead to a false conclusion?
The scientific method is composed of several generalized steps. It isn't an exact method. It is just a common and logical process used to make scientific conclusions. We question our world around us then often hypothesize an answer. We make educated guess on previous experience and prior knowledge. Often we are either told to look something up or feel naturally inclined to do so. In that moment, we do research on the question and hypothesis at hand. This might be casual or in depth. Once in a while we will feel compelled to investigate through an experiment or test of some kind. All experiments and tests should produce some form of data in which it is up to us to analyze. Data is often considered the friendliest to the uses when reported in charts and graphs. After considering our research, prior knowledge, sample size, sample variation, and reported data we must draw the best conclusion possible for our results. Finally, we communicate what we have found.
Other things to consider when conducting a scientific survey or experiment...
1. sample size--not too large, not too small
2. representation bias--must consider who is in our sample and if it is relevant to the population we are studying
3. response bias--must consider that everyone invited will not respond to the offer to participate (consider why that might be)
4. reliability--must be able to produce similar data sets test after test after test in different environments to show the conclusion is reliable
Other things to consider when conducting a scientific survey or experiment...
1. sample size--not too large, not too small
2. representation bias--must consider who is in our sample and if it is relevant to the population we are studying
3. response bias--must consider that everyone invited will not respond to the offer to participate (consider why that might be)
4. reliability--must be able to produce similar data sets test after test after test in different environments to show the conclusion is reliable