States of Water Lesson for Grade 4 Students

Hey there, fourth graders! Today's lesson is all about the amazing states of water and how it morphs from one state to another. Let's dive into this exciting topic together by following a teacher and student conversation. Buckle up, as we uncover the mysteries of water in its solid, liquid, and gas forms. Get ready to be amazed by the transformational journey of water! Let's explore the magical world of H2O and its different states in a fun and interactive way. By the end of this lesson, you'll be water state experts!

States of Water

Image source: EarthHow

Millie had a bad case of flu. Her mother had asked her to inhale some steam. So Millie was in the kitchen, boiling some water. Steam began to come out through the spout of the inhaler. Millie thought how amazing it was that water could now become steam when heated.

When she went to school that day, she sought out her science teacher and asked him how water could become steam. Her science teacher talked to her about the three states of water. Millie already knew about two states – water and steam. He told her to put some water in the freezer of her refrigerator. Just to see if it will turn to ice. And it did. So, Millie was very clear about the three states of water. Anyhow, she further cleared her doubts in the science lesson on the topic. She was quite fascinated by it.

Millie: Mr. Peterson, good morning.

Mr. Peterson: Good morning, Millie. So, what doubts do you have about states of water?

Millie: I know there are three states of water: water at room temperature, steam and ice. But how does water change into the other states?

Mr. Peterson: Oh that happens when water gains or loses heat.

Millie: Let me guess. When water gains heat it boils and becomes steam.

Mr. Peterson: You are right so far.

Millie: And when water loses heat, it becomes the solid ice.

Mr. Peterson: Excellent. You know that water boils at 100o C. That is the boiling point of water.

Millie: Can water become steam without boiling?

Mr. Peterson: It can. It is called evaporation. When water evaporates, what you call as water vapour is formed.

Millie: I guess evaporation can occur at any temperature at any time.

Mr. Peterson: Yes, in that aspect, it is different from boiling. One more difference is that evaporation happens only on the surface of the liquid. But boiling takes place throughout the liquid.

Millie: Also, when water boils there are bubbles formed throughout, right?

Mr. Peterson: You are right. When water evaporates you cannot see any such bubble. One more difference between boiling and evaporation is that during boiling the temperature of the water remains constant but….

Millie: during evaporation the temperature of the water is not constant?

Mr. Peterson: You are absolutely right.

Millie: So that is boiling and evaporation. How about when water loses heat?

Mr. Peterson: alright. Water loses heat sometimes. How do we understand that? Suppose you leave a glass of cold water on the table. After some time, what do you see?

Millie: Droplets of water on the outside of the glass. Yes, I have noticed that.

Mr. Peterson: When water vapour from the surrounding air touches the cooler surface of the glass, it loses heat. When it loses heat, it changes from a gas to a liquid. This is known as condensation.

Millie: That is very interesting. How about when water loses heat?

Mr. Peterson: When water loses heat, it forms ice. That process is known as freezing. The freezing point of pure water is 0oC.

Millie: I see. When water loses heat, it becomes ice. How about when ice gains heat?

Mr. Peterson: That is when ice changes into water. The process is known as melting.

Millie: Let me guess. The melting point of ice is 0oC.

Mr. Peterson: Excellent. Your guess is right.

Millie: How about snow, Mr. Peterson? How is snow formed?

Mr. Peterson: Snow is formed when water in the atmosphere freezes, forming ice crystals. These ice crystals fall to earth as snowflakes.

Millie: Snow is very pretty to look at. I love that all-white look of the earth when it snows.

Mr. Peterson: I agree. Do you know that when you add salt or sugar the boiling point changes? It increases. So sweet or salty water boils at a higher temperature.

Millie: That is very interesting. So sea water will have a higher boiling point.

Mr. Peterson: Absolutely. Similarly, when you add other substances to it, water behaves in weird ways. Its freezing point decreases. So, when we say that water boils at 100o C and freezes at 0oC what are we referring to? We are referring to pure water.

Millie: I see. That is good to know. Talking to you is always very interesting, Mr. Peterson. I have to go now. Thanks a lot for all this information.

Mr. Peterson: Bye Millie. See you in class.