Scientists Infer

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Objective

SWBAT differentiate between evidence and inference, understand that evidence is drawn from observations and data collection made during scientific research, and construct inferences based on observations and data as their evidence.

Big Idea

Scientists make inferences based on evidence that is collected throughout the scientific process. Inferences and evidence are two very different things, but are both essential to the scientific process.

Engage

5 minutes

I start the lesson by projecting the an image and allowing the students about a minute to view it.  After a minute has passed, I ask the students to write a list of observations they make about the image. (The image I chose was deliberately selected. I explain the reasoning for this choice in my reflection.)

I ask for volunteers to share the observations they have made. Students say things such as, "The kids are chasing pigs,", "They are at a farm," and, "They're having fun, but the pigs aren't!" As I call on students to share their observations, I record them on chart paper, placing them into two categories.

The students are not told how I am categorizing their ideas, but soon realize that I am sorting them strategically. Naturally, the students start to ask and make guesses as to how I am sorting their ideas, and even start to predict where each idea will be placed. I do this purposely, as I want them to think about how and why I am sorting their observations and to come up with their own rules for sorting. This helps to activate their attention and thinking, as well as encourage higher order thinking, even if their guesses are not correct. 

What they do not know is that I am placing observations into one category and inferences made using these observations into the other. At this point, students usually don't understand the difference between the two. I tape the chart paper to the wall, letting the students know we will come back to it later in the lesson.

Explore

30 minutes

I have prepared a backpack filled with several items before class has started, such as a pink baseball cap, two books about horses, a movie ticket stub, a box of band-aids, hair ties, a softball glove, and a 1 Direction t-shirt.  I show students the backpack and ask them to use scientific thinking to learn more about this backpack. I give them 3-4 minutes to inspect the contents of the bag and then direct their attention to the whiteboard.

I draw a large T-chart on the board, but do not include titles. I have students copy this in their science journals.  Next, I ask students, "What can you observe about the bag and its contents?", prompting students to describe the backpack and the contents inside, and writing their observations in the left column of the chart.  Most students will describe the size, color, and style of the bag and of objects as they are shown.

Next I prompt the students to explain what they can infer about the person who owns the backpack, based on the information they have acquired.  I make sure to use the word "infer" several times, even if it is new to most students. I also call on 2-3 volunteers to provide responses before having them write their inferences in the right column of their chart. I choose volunteers instead of random students because I am not concerned with holding all students accountable for knowing the information just yet. Many students have heard the term "infer" used during reading, so they will be able to come to a conclusion about the meaning. Those who haven't heard it will begin to understand its meaning after hearing the responses from their peers. Once we have developed a shared understanding of the terminology, then I can start holding them all accountable for the meaning and will select students more randomly.

I write the words "evidence" and "inference" next to the T-chart, and discuss these terms with students. I explain that evidence is data that can be measured, observed, examined, and analyzed. Next, I explain that inference is an educated guess or explanation that can be derived after analyzing the evidence. I work to further develop meaning for these words by relating them to the work of paleontologists. Paleontologists study fossil remains, collecting evidence of prehistoric animals through the observations they make. Paleontologists then make inferences from the evidence they uncover. For example, A shark′s tooth embedded in a fossilized bone may lead a paleontologist to infer that a shark bit the animal.

After describing the differences between evidence and inference, I ask students to place these two words at the top of the T-chart, using them as titles for the appropriate columns.

Next , I place the students into groups of three and give each student group a different image from the Evidence vs. Inference PowerPoint. (I have printed them on cardstock and laminated them for easy reuse.) I explain to the class they they will have 2-3 minutes to examine the image and record all of the evidence and inferences that they can. After time is up, they will pass their image to the group on their right, and follow the same process for the image that was just given to them. This process will repeat 4-5 times in order to give each group ample practice in identifying evidence and making inferences.   As students work, I play the Evidence and Inference Song, projecting the lyrics for students to read. I restart the song with every new image. Soon enough, students are singing along, further creating schema for these concepts.

In addition to monitoring student discussion as they work, I also circulate around the room, asking questions to provoke thought and spark group discussion. Some of my questions include:

  • "Is that an inference or is that evidence?"
  • "What evidence do you have to support your inference?"
  • "What can you infer from the observations / evidence you have found?"
  • "What does that evidence lead you to believe?

Explain

10 minutes

After students have had time to view 4-5 images and record their inferences and evidence, I regroup them so that they are sitting in groups of four, with students who have not seen any of the same pictures as themselves. I try to make sure there is one child in each group who has seen each picture, in order to keep the conversations going throughout the entire lesson. I slowly show each image under the document camera (You can show them on the projector or just hold up enlarged versions of the image if you don't have a document camera) and ask students who examined this picture to share with their group at least three pieces of evidence they collected, as well as two inferences they have made. (This is a modified version of a Jigsaw strategy.) Their partners have to listen to their thoughts and decide if they correctly identified evidence and inference about each picture. If they agree, they place their finger on their nose, signifying to me that their classmate correctly identified both. If they disagree, they must question their partner about their choices and/or justify why a change is necessary, until all members of the group come to a consensus as to which pieces of information are evidence and which are inferences.

Next, I direct the students to their journals, where we have previously glued in the "What do Scientists Do*?" chart. I direct their attention to the section entitled, "Scientists Infer". I have students summarize what it  means to infer and to use evidence to support their inferences. I do not provide further discussion, as I want students to write independently for this section, and I also want them to write what makes sense to them, in order to personalize the learning and provide a more tailored description for them to refer to in their journals at a later date. 

*The "What do Scientists Do?" paper will be used throughout the unit. It is best to have students keep it in their science journal or another place where they can return to it throughout each lesson in the unit. We will add to it as we build understanding and study each trait of a scientist.

Elaborate

10 minutes

Once I am confident that all students are fluent in identifying and distinguishing between evidence and inference, I extend the learning by providing a more hands-on activity that I am able to relate to scientific processes.

A day before conducting this lesson, I have filled several "mystery boxes" with random objects, such as nails, bouncy balls, rocks, marbles, jacks, rolls of masking tape, etc.  I have purposely tried to use objects made of differing materials, and of varying sizes, weights, etc. Some boxes have only one type of item, while others contain several. No two boxes contain the same contents. I have wrapped each box in brown butcher paper to make them as indistinguishable as possible from the outside. I number each box so that the students can easily find it again if they want to collect more evidence later.

I remind the students that scientists often construct knowledge by making inferences about little known concepts after collecting as much evidence as possible. As scientists they will be doing the same. Their task will be to collect evidence and make inferences about the contents of the boxes (Science and Engineering Practice 1 - Asking Questions and Defining Problems - Ask questions that arise from careful observation of phenomena, models, or unexpected results, to clarify and/or seek additional information.)

Before starting, they create another T-chart in their science notebooks with the appropriate titles. Then they have about 7 minutes to collect and record evidence and make inferences in their notebooks.

When time is up, students pass their boxes around the classroom, calling on a group reporter to share their evidence and inferences with the class. (Students have the option to use discussion frames that are posted in my classroom.) I allow for a few additional inferences from other students, provided they can support their thinking with evidence.

After each group has shared, they will want to know what is in each mystery box. I explain to them that there are many cases in which scientists never get definite answers to their questions and often cannot confirm whether or not their inferences are accurate. I let them know that this is one of those times. It will drive them crazy not knowing what is in the box, but it encourages them to study these boxes in the coming days, getting them to continue to think scientifically, which is definitely a good thing!

We briefly revisit the chart paper, and I ask students to think silently for 20 seconds about how I categorized the observations they made earlier. After 20 seconds has passed, I call on a student or two to share their thoughts. After teaching this lesson for over 7 years, I have never had a student get this question wrong!

Evaluate

5 minutes

I have the students return to their own seats and I conduct a read-aloud with The Important Book, by Margaret Wise Brown. before beginning the read aloud, I tell the kids that they may not understand what this book has to do with evidence and inference, but it will make sense soon.

While conducting the read-aloud, the students will become familiar with the pattern and rhythm of the book and will share the ending of each page before you read it. I want them to do this, because the evaluation part of the lesson depends on them recognizing the pattern of the book. I encourage this by pausing before the last sentence of every page so they can say it before I do. This usually happens by the fifth or sixth page.

After finishing the read aloud, I pass out the Important Book Reflection Form to each student. I direct the students create their own "page" of the book - one for evidence and one for inference. They must not only follow the pattern of the book, but must also clearly describe attributes of both terms, which gives me a great deal of insight into their understanding of the new terminology.

I also have the students complete the "What do Scientists Do*?" paper in their science journals. This allows them to summarize their learning and provide a place to refer to later if they need additional prompting or support.

*The "What do Scientists Do?" paper is used throughout the unit. It is best to have students keep it in their science journal or another place where they can return to it throughout each lesson in the unit. We add to it as we build understanding and study each trait of a scientist.