Ways to Classify Objects

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SWBAT realize that there is more than one way to classify objects.

Big Idea

Students often classify objects by size and shape. Now they will look more at the properties of objects such as hardness, flexibility and texture.

I Can Statement

5 minutes

We begin today's lesson by reading the I Can statement together. It says, I can classify objects in at least 3 different ways. 

I ask students if they understand what classify means in this sentence. I want to make sure that the I can statement is clear before moving forward with the lesson. It is important to clarify new vocabulary for students.

We discuss what the word means. I have students turn and talk to a partner about their understanding of the word. This gives everyone a chance to express his/her understanding of the term before moving forward.

I ask students to share examples of things they have classified in the past. 

Classifying Together

45 minutes

I bring students to the rug for the beginning of this lesson. I display a variety of objects on the rug including white cotton, a rock, a piece of white paper, a piece of tin foil, a piece of wood, a small red rubber ball and a hard solid plastic red triangle.  I say, "I want you to look at the objects on the rug. Can you find any that you think belong together?" Finding Different Ways to Classify ObjectsI let students group different objects together such as the white cotton with the white paper and red ball with the red triangle. They might also group the rock with the wood, etc. I ask each student, "Why did you put those objects together?" I want them to verbalize the categories they are choosing. I let students share their ideas for about 5 minutes in order to keep the lesson moving. If other students still have ideas, I tell them that I know that everyone has good ideas to share but that today we are going to only share some of the ideas. They may be able to use their ideas in the next part of the lesson.

I tell students, "today you will be working as scientists to test materials in several centers. Each center has a way to classify the objects. You will need to find a way to test the materials to figure out which ones belong to the category and which ones don't, or which ones are the hardest and which ones are the softest. You will record your ideas on your journal page.

There are scientists who are called materials scientists. They study materials to see which ones would be best for a particular job. My friend who is a materials scientist tries to figure out which materials would be best to use to make screws for a submarine. It is hard to believe that people have to really study to see which materials would be best for a job. Imagine if you tried to build a car out of cardboard. What would happen as you tried to drive down the highway?" (I take someone's answer before continuing on). "What if I built a swimming pool out of paper? What would happen when I filled it with water?" Again I call on a student to tell us what would happen.

"That is why it is important to think about how materials work. We talked about the term matter the other day. Do you remember what it was?" (Something that takes up space and has mass) "We want to study some of the things that make matter different and the same, just like a materials scientists would so today you will visit 3 centers."

"At the first center* you want to try to arrange the materials from hardest to softest. You can experiment with the materials but you can not break or cut them so think about how you will test the materials to see if they are hard or soft and then record what you did and your results in your journal."

"At the next center** you will test the materials to see which is the easiest to bend, and put them in order from easiest to hardest to bend. Again, please do not cut the materials and try not to break them. Record what you did and your results in your journal."Classifying by the Material It Is Made Out Of

"At the last center*** you will test the materials to see which one is the roughest to the smoothest. Again, record your findings in your journal."

"At each center you will have about 7 minutes to work and then 3 minutes to record your findings. I will ring the bell to let you know when it is time to record your results. You may work as a small group, or individually at each center."

"I want you to remember that there is not just one right answer to how we sort the objects today, but I do want you to be able to explain why you put the objects in the order you did. You will have new partners to explain your work to after we visit the centers today."

I ask for questions and then use playing cards marked 1 - 3. I show the numbers 1 - 3 at the centers and tell students they should go to the center that matches their card. This process makes it quick and easy for students to divide into small groups.

The centers have the following materials as well as a sign at each one telling how they are trying to sort:

*Center 1 - cotton, rock, cloth, plywood, balsa wood, a pencil, a paperclip and a stainless steel fork

* Center 2 - a pencil, a paperclip, a straw, a pipe cleaner, a popsicle stick, a crayon, a one inch thick piece of a stick, a metal bolt

***Center 3 - sandpaper of 2 different grits, a mirror, a piece of burlap, a piece of felt, a smooth plastic block, a large bolt, a piece of paper

(Note that students may ask for items to use to test their materials. These can be provided as appropriate. I try not to say that there is any right or wrong answer to these sortings. This is more about how students justify their choices for the order of materials. In the next section students will have a chance to justify their choices to one another.)

Students work in their centers for about 7 minutes and then have 3 minutes to write in their journals. I ring the bell to let them know when to move to the next center. I circulate around as students work to ask questions and hear how they are classifying the objects. I hope that they will move beyond just looking, but will actually explore how the materials may feel as they attempt to classify them. 



Explaining Our Choices

15 minutes

After students have visited all 3 centers I ask them to take their journals Journal page  Journal Page 2 and remain at their centers. I tell them that now they will work in groups of 3 (one from each of the 3 center groups) and share how they classified the objects. Each student must tell what he/she did and then answer questions from peers about their choices. I give each student 3 question cards. One says, "why did you put them in that order?" One says, "why is that object there instead of here?" and the final one says, "Question of your choice." I show the class the 3 cards as I hand them out. I explain that they will each need to use at least 2 of their questions during the next 15 minutes. Once they use a question they can put it in the middle. They should ask their partners one of the questions after each person shares. 

I demonstrate by putting the original objects from the rug in order and then saying, "If I was the listener and I saw this order, I might use the question, "why did you put this one (pointing to one object) here instead of there (pointing to another place in the line). My partner would need to explain that he put that one there because when he tried to bend it, it didn't bend at all, but the other one did. "

I call one student from each group to move together to share. I continue until everyone is grouped. As students begin to share I circulate around to listen to reasoning and to encourage students who may be struggling with sharing. I note the reasons students use for classifying. I also collect the journals at the end of the lesson so I can evaluate student understanding of classification. 

The reason that I call one student from each of the centers is to make sure that students can not rely on the reasoning of someone else from their original group. They need to explain the order they have chosen on their own. I want all students to begin to discuss their scientific ideas. By asking each student to share and to ask a question, I am encouraging this discussion.


5 minutes

After everyone has had a chance to share and explain their thinking, I ask everyone to return to their seats.

I ask them to read the I Can Statement. Did they classify objects in 3 different ways? 

I ask for final thoughts about what they did and what they found out before ending today's lesson to make sure students have time to process their thinking before we move on to another lesson tomorrow.