Motion and Molecules

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SWBAT simulate and explain how water takes on different states and what causes them.

Big Idea

A fun review with students on how we can simulate the molecules that are found in water by moving around the room and using a flashlight.

Three States of Water

5 minutes

When reviewing the states of water, students were having a hard time explaining their encounters with it. To help them I ask them about the shapes and forms that water can take. This helps them and I soon have students answering with liquid we drink and ice too.

I write down the the three states of water onto the white board and include an example for each one. I then ask if anyone can explain how water can transform and change into these different states. Instead of giving them the background, we are going to participate in an activity to learn about the effects energy has on the molecules that make of water. The only piece I give students is that water is made up of molecules, I draw the picture of what a water molecule would look like. I then have student stand up and explain that they are going to be a water molecule. Their body is the oxygen molecule and attached to it are two hydrogen molecules. They model this by placing their hands on their hips. Each elbow curve is the attached hydrogen molecule. 

Water Molecules in Motion

10 minutes

Now that they have learned how to transform into a water molecule, we are going to proceed with our experiment. This activity is an adaptation of a Project Wet activity.  

I explain that when it is a students turn they will come to the center of the desks and will pretend to be a water molecule. I further explain that water molecule move and depending on their movement is how we get the different states of water. I call on five students to model for the class one of the states of water. At this time, I have not explained or taught them how the molecules will move based on their state. I explain that molecules will move slow, medium, and fast.

I ask the five students and the class how they think that steam might move. I have some pretty crazy responses and then I remind them to refer to slow, medium, and fast. A student says fast, and confirm and ask the five students to act this out. I let them do this by jogging. We continue this for water and ice. I call on five different students each time. 

Once we have identified the speeds of the molecules, we are ready to talk about the space between the molecules. Students had an easier time determining this and we talk about this space as what gives water its shape of solid, liquid, and gas. 

Predict and Model

10 minutes

We have not discussed the importance of temperature to our states of water. I ask students to go back to turn and talk about what influences water to change its state. I let them discuss for about two minutes. As I walk around and listen, most of my groups are on the right track. One group discusses a ice maker and another is explaining what happened to their garden hose over the winter. I then ask a few of these groups to share their discussions. 

I facilitate and prompt their learning until they determine that temperature like heat make a difference on the state water will take. The class works together until they agree that ice is formed when the temperature is freezing cold, and gas is when it is heated up like on their stove.



5 minutes

Now that we have established all the parameters and states of water, we can play a game. First we practice changing the state of water with heat and cold. I do this by calling on five students to model again, and this time I hold up a red, blue, or tan card to tell the group what the temperature is. I hold the card up and my "water molecules" have to move accordingly. This time I do not tell them what to be, I just hold up the card. With another group, I ask them to act like water and then turn into a gas. I do the same with water to a solid. For a challenge, I ask a group to act like a pot on the stove. I have prompt them that some water stays water and some turns to steam. So they model that for the class. 

To conclude, I let teams of five decide what they are going to model for the class. This time the class has to determine based on the acting out what state of water the group is and the temperature. We do this so that every group has a turn. I can determine quickly which students understand the lesson by how they play charades.