You hear the crack of a bat hitting a baseball followed by the sound of breaking glass. You infer that the flying baseball broke a window. An inference is a logical explanation based on observations and prior knowledge. It attempts to explain an event based on the information that is available to the observer. Making an inference is a science process skill that is a component of many types of inquiry-based activities.
Inferring is a thinking skill related to predicting. Like a prediction, an inference is based on observations coupled with previous knowledge or experience. A prediction is a statement about the future: what the student thinks will happen. An inference is a statement about the past: what the student thinks has happened.
Inferences are not always correct because they are based on incomplete data. Limited observations, inaccurate prior knowledge or misconceptions may lead to incorrect inferences. Students may change their inferences as they make further observations and gather more data.
Students can make inferences to explain processes that they can't easily observe, such events that happened long ago and processes that occur slowly over time. Other good topics for inferring activities include processes inside the body and identifying an unknown substance or object.
Activities that involve constructing or using models encourage inferring because students must infer what the models represent. For example, students construct a model glacier and infer that glaciers weather landforms as they flow.
---Observe weathered rocks such as river rocks and sandstone to infer how water and wind weather rocks.
---Observe mold forming on a slice of bread. Continue to observe the bread for a week and then infer the role of mold as a decomposer in an ecosystem.
---Observe teeth in skulls or skull models of several different animals to infer which animals eat plants, animals or both.
---Place some uncoated iron nails in a jar of tap water and some in a jar of salt water. Over time, observe changes to the nails and infer how salt promotes rusting, a chemical change.
---Observe resting heart rate. After jumping rope for one minute, take pulse and infer that the heart pumps blood faster during exercise.
---Place a metal spoon and a plastic spoon in a beaker of hot water. Wait five minutes and touch each spoon. Infer why the metal spoon feels warmer than the plastic spoon.
Conducting the Activities
A modified K-W-L chart can serve as a graphic organizer to show the process of making an inference: replace "What I know", What I want to learn" and "What I learned" with "What I observed", "What I know" and "What I infer". Students can record their prior knowledge before the activity and their observations during the activity.
After students make observations, they can compare them with what they already know about the subject and ask themselves if their observations support their prior knowledge. Then they make an inference to explain what happened by using the facts they have available to them and record it with their observations and prior knowledge. To test an inference, students can gather more information to support or oppose their inference.
Inferring is sometimes confused with drawing conclusions. Students draw conclusions when they analyze all of the data they gathered to explain what happened. Unlike inferring, it is wholly based on verifiable data.
- Skills Handbook Using Science; William C. Kyle Jr. and Brenda Webb; 2004
- PAKS: Parents-and-Kids Science; Danny McKenzie; 1996
- Science Series: A Teacher's Guide to Student Discovery through Inquiry
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