Education and
Public Engagement
at the Lunar and Planetary Institute
Explore! Ice Worlds!

Ice and Seek: What is Ice?


In this two-part, 60-minute activity, children, ages 8 to 13 begin exploration of ice on planets and moons in our solar system by building an understanding that there are different types of ices. As teams, the children examine three types of ice — dry ice, alcohol ice, and water ice. They identify the ices based on clues then match the type of ice to the appropriate planet or moon on which it occurs.

What's the Point?


For each child:

For each team of three to four children:

For the group:

For the facilitator:



1. Prompt a discussion about ice. The children may refer to the snow mobile they created in States of Water.

Share with the children that there are lots of substances around us that are solid, but we do not call them ice. We say that windows are made of solid glass (or glass) but we don't say they are made of glass ice. Metal scissors or staplers are made of solid metal, not metal ice. Scientists who study planets use the special term "ice" to refer to substances that usually are liquid (or gas) on Earth, but that form solids on other planets or moons or in comets. On Earth, carbon dioxide typically is a gas and ammonia is a liquid. On some planets there is no water ice, but there is lots of dry ice!  Other planets have ammonia ice.

2. Distribute — or display — the images of ice on earth. Ask the children to examine the images.

3. Share the images of ice on other planets. Have the children carefully observe the images.

4. Divide the children into teams of 3–4 and explain that each team will examine different types of ice that occur on other places in our solar system. Based on clues they will receive, their mission is to discover the identities of these ices.

5. Have the children examine the Ice and Seek "Instructions", "Team Observations", and "Ice Characteristics" Sheet. The Ice and Seek Team Observations sheet will help the children make their observations of the different ices. Based on their observations, the children will work in teams to identify the different types of ice using the "Ice Characteristics" sheet.

6. Review with the children how they should conduct their investigation. Reinforce the importance of proper handling of the ices! Dry ice can cause frostbite. Do encourage them, however, to use the tools at each station. At each station they should:

7. After all the teams have examined the ices and completed their Ice and Seek "Team Observations", gather the large group together and allow the teams to share their answers. Discuss what they have learned.

8. Discuss their observations of the different ices. Ask the children if they noticed what looked like smoke coming from the dry ice. Explain that dry ice is actually frozen carbon dioxide (CO2). Carbon dioxide is a very common gas. It is what we exhale when we breathe and what plants need to survive. When a substance changes directly from a solid like dry ice into a gas, we call the process sublimation. Dry ice, under Earth's normal surface conditions, does not melt into a liquid, it sublimates — or turns directly into a gas. What looked like smoke was really cold carbon dioxide gas sublimating from the ice. Water ice can do the same thing; in very cold conditions, like those in Antarctica, water ice can sublimate — turn directly into water vapor.

Ask the children if they noticed that the alcohol ice was a little slushier than the water ice. Have them reflect on what they learned in The Melting Point activity about the various freezing and melting points of different substances. Share that alcohol has a lower freezing point than water, so the temperature has to be colder before it will freeze. Water freezes at 32—F (0°C). The freezing point of alcohol depends on the type of alcohol being used, but it must be much colder than water to freeze. Explain that you were able to get these samples to freeze by mixing them with water to bring their freezing points up a bit. But, even so, the alcohol could not be frozen solid.

9. After discussing the types of ices, distribute an "Ice Across the Solar System" sheet? to each child. Call the children's attention to the wall where you have placed the planetary ice data set sheets. Explain that these are images of planets, moons, and icy bodies — like comets — in our solar system. Each image on the wall includes information about the presence — or lack — of ice on that body along with the type of ice. Based on the information found on the planetary ice data sheets, their mission will be to identify, as a team, which planets and moons have ice and what type of ice it is.

10. Play Ice and Seek! Invite the teams to take their "Ice Across the Solar System"? sheets and begin their investigations! Explain to the children that they should travel as a team to each image, read the information about that planet, moon, or comet, then record on their sheets whether that planetary body has ice and, if so, where and what type of ice it is. Not all of the planetary bodies have ice, and some may have more than one type of ice in more than one place!


11. After all the teams have examined the ices and each child has completed his or her "Ice Across the Solar System" sheet, gather the group together and discuss what they have learned.

Tell the children that in the next activity, they will learn how scientists have discovered ice in very faraway places…as far away as the edge of our solar system.