A Crazy Colloid
Description of lesson: Students will experiment with a substance called Goop. They will describe the properties of the Goop and predict what form of matter it is in.
Grade level: I will use this lesson with a first grade class. The Alabama Course of Study p.23 number 1 says: Students will observe that objects in the world vary greatly in their properties (size, color, taste, shape, texture, and odor).
Number 2 says: Students will describe findings from investigating solids and liquids.
Matter is anything that has mass and takes up space. Mass gives an object the property of weight and inertia (resistance to change in the motion of an object). There are four states of matter, solid, liquid, gas, and plasma. If something is in a solid state of matter, it has a definite shape and volume. The volume of an object is the amount of space it occupies. A block of wood placed on a table retains its shape and volume, therefore, it is an example of a solid. If a liquid is poured on that same table, there are very different results. The liquid will flow out over the surface because it does not retain its shape. A liquid takes that shape of its container. If something is in a liquid state of matter, it will have a definite volume, but an indefinite shape. Air fills a balloon. If a hole is placed in a balloon, the air will rush out. If an object is in a gaseous state of matter, it will not have a definite shape or a definite volume. Plasma has all of the properties of a gas except that it is made up of electrons instead of atoms or molecules. Plasma exists on stars, in necular explosions, and neon signs.
Water is an example of a substance that can exist in all forms of matter. Ice is solid, water is liquid, and steam is gaseous. The particles in a solid are closely packed and held in fixed positions. This gives solids their definite shape and volume. The particles in a liquid are close together, but they are not bound to fixed positions; they can slide past and around each other. This enables liquids to take the shape of their container and to flow when they are poured. The particles in gasses are widely separated. Their positions have no order at all and they are constantly in motion and expand to available space.
Properties are characteristics that enable us to distinguish one kind of matter from another. A physical property is observed with out changing the object in any way. The melting point or boiling points of an object are examples of physical properties. Extensive physical properties are thing like mass, length, and volume. They depend on the amount of matter present. Intensive physical properties do not depend on the amount of matter. Examples of Intensive physical properties include melting point, boiling point, density, ductility, malleability, color, crystalline shape, and refractive index.
A physical change is a change in matter that does not result in a change in identity. Changes of state, from liquid to gas, and solid to liquid, are physical changes. If a substance does undergo a change that alters its identity, then it is a chemical property. Any change where one or more substances change into substances with different properties is a chemical change or a chemical reaction.
In every chemical or physical reaction, energy is either absorbed or released.
When water is changed to a solid, it releases heat. This is called an exothermic reaction. When hydrogen combines with oxygen to form water, heat is also produced.
"Colloidal substances have properties of both solid and liquid states of matter. In a colloid, one substance is suspended in another. The suspended material is made of particles so small they don't sink to the bottom of the second substance. Other colloidal substances include fog, smoke, meringue, protoplasm, homogenized milk, synthetic rubber and mayonnaise" (taken from the CTM 403 notebook, page 430, written by Dr. Michael Kamen).
Concepts Covered in the Lesson:
Solids have a definite shape
Liquids do not have a definite shape.
Liquids take the shape of the container that they are in
Materials and Equipment:
To make Goop: In a large bowl, combine: 2 cups of Elmers glue (16oz, not school glue), 1 ½ cup of water, food coloring. Mix well. In another bowl, mix: 1 cup of hot water, and 1 T of Borax (found in laundry detergent section) until it dissolves. Slowly poor Borax mixture into the glue mixture. Knead with hands until liquid is absorbed.
Plastic baggies to store Goop; straws, tooth picks, Popsicle sticks, etc. for exploration; plastic cups, charts of solid and liquid properties, newspapers.
1. The class will review liquids and solids. I will ask them what they wrote in their matter journals. I will ask them why they think that what they drew was a solid (definite shape) or a liquid (forms to its container, changes shape easily).
2. I will tell the students that I have a very special treat for them today. "I have a special substance called Goop and I want you to help me experiment with it".
3. I will show the students the ingredients used to make Goop and ask them to tell me what state of matter that the individual ingredients are in. We will talk about why they are solids or liquids, emphasize the rules for states of matter. Have students point out the reasons on the charts of the states of matter.
****Glue, food coloring, and water are liquids because they take the shape of their containers. Borax is a solid because it does not change its shape easily and has a definite shape.
4. Tell the students that they have five minutes for free discovery and observation with the Goop. Suggest that they pull it apart, put it back together, roll it, bounce it, and stretch it as far as they can. I will encourage the students to share the Goop and to discuss their findings with their group members. I will give the class a signal that will let them know that it is time to put the Goop into their plastic cup and to put their heads down and be silent.
5. I will ask the students to look at what happens to the Goop when it is in the cup. Tell one person in each group to drive their finger straight down into the Goop. Then have them slowly push their finger into the mixture. Is there a difference?
6. I will bring around straws, toothpicks, Popsicle sticks, newspaper to test if it picks up newsprint. Let students experiment for a few more minutes.
7. In a whole group again, I will show the students a sample of Goop in a plastic bag and ask them how it looks. They should tell me that it forms to the bag, which is a property of a liquid.
8. Talk about what the students observed during their exploration. Ask them:
What does Goop look like?
What does it feel like?
What does it smell like?
Does it make a sound?
What else did you observe about Goop?
****Record the data on a Goop web.
9. Ask the students how Goop compares to its original ingredients. Look over the states of matter charts again and compare them with the Goop web. Ask them what state of matter that they think Goop fits under. Have the students explain their answers.
Students will write a journal entry about Goop. They must say how Goop acts like a state of matter. They must also write one other interesting thing about Goop.
Ex.: Goop acts like a liquid. It forms to the cup.
Science Process Skills:
Classification of solids and liquids
Observation by touch, smell, see, etc.
Oral communications with group members.
Written communications in journals.
The hands-on learning portion of this lesson was amazing to witness. Students were given a substance, Goop, which has properties of a solid and a liquid. The students were enthralled by the substance. They experimented in ways that I had not even thought of. It was very meaningful to the students to be able to touch and manipulate the Goop in any way that they chose. They did not just follow direct instructions from me, but discovered the Goop individually and were able to draw their own conclusions.
During the discovery portion of the lesson, I should have talked to each group about what they were discovering about the Goop. I should have asked them questions that would further their understanding of the concepts that I wanted them to get from studying Goop. I should have taken notes about what the students said to me about Goop, so that I could recall it later in the colloquium. I also could have tried to make this portion of the lesson more "science related". We could have discussed how scientists experiment with new substances. I could have encouraged the students to explore the Goop in the same manner.
In the colloquium, I tried to lead the students in their discussion of Goop. I should have allowed the students to talk with each other and to draw conclusions as a group. I was concerned that first graders would not be able handle this responsibility, but I should have tried to get them to think more critically. I was worried that the students would not realize the properties of solids and liquids in Goop. I wanted to tell them the answers instead of letting them figure out the knowledge themselves.
I did not use the scientist's log approach to the colloquium. I did not ask the students to agree on statements that they believed to be fact. If I teach this lesson again, I will be sure to include a scientist's log. This helps the students to think critically and encourages them to talk to the members of their group. From looking at the students' assessments, I do not think that they grasped the concept of solid and liquid properties of Goop.
My assessment of the students was a journal entry. Some of the students wrote what I was looking for, but many of them just described the Goop. They said that it was gooey, or felt like rubber. I wanted them to write about if it was a solid or a liquid and what qualities of each it possessed. When I interviewed three students for another project, I learned more about what the students understood about solids and liquids than I did in their journal entries.
Next time, I might have the students write a group proposal about whether Goop is a solid or a liquid. The students could learn from each other and they could debate the solid and liquid status. They might be more likely to realize that Goop acts as both a solid and a liquid. I learned a lot from this lesson. I hope to improve it next time.