Ask the students if they know what a solid, a liquid or a gas is to determine prior knowledge on which you can build. Show the students a glass of water, an ice cube and a picture of a boiling pot of water with steam coming off of it. Ask them what the items are and if each one is a solid, a liquid or a gas. Teach your students the "Three States of Matter" song (songsforteaching.com/jennyfixmanedutunes/3statesofmatter.htm).
Explain to the students that they are going to conduct their own experiments. Give each student a small book with three pages each. Have the students write "Matter" on the cover and explain that they are going to document their findings in the booklet.
Give each student a bottle of water and a clear plastic cup. Ask the students what state of matter the water is in -- liquid, solid or gas. Have them write "Liquid" on the first page of their books and instruct them to draw a picture of the water. Have the students write their names on their bottles and their cups.
Instruct the students to pour some of the water from their bottles into their cups. Have them recap the bottles. Explain that you are going to put the bottled water in the school freezer. Ask the students what they think will happen to water. Tell the students to write on the second page of the book what they think will happen to the water in the freezer.
Instruct the students to draw a line on their cups to mark how high the water is filled. Explain that they are going to leave the cups of water in the classroom overnight. Ask the students to predict what they think will happen to the water when left in the classroom overnight. Tell them to write their predictions on the third page of their books. Place all of the cups onto a tray and place them under a lamp.
Return the students' water bottles and plastic cups the next day. First, have them look at the bottles of water. Ask them to explain what happened to the water. Tell them to write their findings underneath their predictions on the second page of their books. Then have them look at their cups of water. Tell them to mark the point to which the cup is filled on the cup. Ask them if they notice a difference. Tell them to write their findings underneath their predictions on the the third page of the book.
Ask the students if the water in the bottle is a liquid, solid or gas. Have them write "Solid" on the second page of their books. Tell them to draw a picture of the frozen water. Ask the students what they think happened to the water in their cups. Explain that the water did not disappear; it still exists, but it evaporated and is now in tiny pieces in the air. Explain that this water is just like the steam they saw in the picture of the boiling water. Ask the students if the water in the air is a liquid, solid or gas. Instruct them to write "Gas" on the third page of their books and to draw a picture. Discuss in what way the water is still water, regardless of which state of matter it is in.