Summary

In this lab, students will think critically about the properties, structure and function of materials as they design and build a device used to insulate an ice cube to prevent it from melting.  

Grade Level

Elementary and Middle School

NGSS Alignment

This lab will help prepare your students to meet the performance expectations in the following standards:

• K-2-ETS1-3: Analyze data from tests of two objects designed to solve the same problem to compare the strengths and weaknesses of how each performs.
  
• 2-PS1-2: Analyze data obtained from testing different materials to determine which materials have the properties that are best suited for an intended purpose.
• 3-5-ETS1-1: Define a simple design problem reflecting a need or want that includes specified criteria for success and constraints on materials, time, or cost.
• 3-5-ETS1-2: Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
• Scientific and Engineering Practices:
  • Developing and Using Models
  • Planning and Carrying Out Investigations

Objectives

By the end of this lab, students should be able to:

• Compare and contrast the insulating properties of various materials.
• Offer a basic understanding of heat transfer.
• Describe the phase change process of melting.

Chemistry Topics

This lab supports students’ understanding of:

• Energy
• Heat
• Heating and Cooling
• Phase changes

Time

Teacher Preparation: 10 minutes
Lesson: ~1 hour

• Introduction: ~10 minutes
• Build Device: ~20 minutes
• Complete Test: ~20 minutes
• Post-lab Discussion: ~10 minutes

Materials

• 2 Ice Cubes (per student)
• 1 Plastic Cup (per student; cup should be approximately the size of a solo cup)
• Tape
• Timer
• Various insulating materials (examples: aluminum foil, cotton batting/balls, bubble wrap, polyethylene sheets, newspaper, felt, plastic wrap, cotton/material pieces, etc.)

*Optional Extension Activity:

• Large bowl of water with ice cubes
• Large Ziploc bag
• Small rubber glove
• Crisco

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• Food in the lab should be considered a chemical not for consumption. Ice cubes should not be put in a student’s mouth.

Teacher Notes

• This lab was modified from the original high school version, Chemistry is Cooler Stress Test Challenge for use specifically in the elementary or middle school classroom. It was developed as part of the AACT Strategic Plan and the work of the AACT Grade-Level Ambassadors.
• Plan to have at least 2 ice cubes available per student. Ice cubes should all be the same size/shape.

Activity 1- Ice Cube Melting Race

1. Pre-Activity Questions

• Prior to the activity, discuss these opening questions:
  • What does the sun provide? (examples; heat and light)
  • How is temperature measured? (thermometers)
  • Why is the temperature different in different places? (the shape and tilt of the earth)
  • What are the challenges of living in a cold environment? (finding warmth, food production and/or storage during winter, shelter)
  • How can you protect yourself from the cold? (shelter, proper clothing, heat sources)
  • What are the challenges of living in a warm environment? (too much light and too much heat)
  • How can you protect yourself from heat? (shade, air conditioning, water)

2. Introduce the Activity

• Introduce the lab by telling students they are going to have a race! Each student will be given an ice cube and will race to see who can completely melt their ice cube first. I suggest that the teacher implements some safety ground rules, such as:
  • Students may never put anything in the lab in their mouth so make sure they understand that using their mouth is not allowed as part of the race.
  • Students may not throw the ice cubes to shatter them.
• When conducting the race, students will choose different methods to melt their ice cubes. Some students may choose to rub their ice cubes rapidly back and forth on a rough surface such as carpet, while some students may use their body heat from their hands to melt the ice cube. Always be aware of what the students are doing and use good judgement if something is safe or appropriate.

3. Discuss Science Concepts

• After the race, discuss the strategies that worked well and the strategies that did not. Probe students to think about what happens scientifically. Discuss heating, cooling and phase changes.
• I suggest showing two short BrainPop videos to help students better understand the concepts:
  • BrainPop Video: Heat
  • BrainPop Video: Heat Transfer
  • *Teachers should always preview videos prior to showing them to students. There are BrainPop quizzes available that may be helpful to use for an assessment if needed.

Heat Transfer

Explain to students that when two objects or substances are touching and they are at different temperatures, heat always moves from the one at higher temperature to the one at lower temperature. 

Ask students if they think there was heat transfer in the activity they did while trying to melt the ice. 

Explain, or have a student explain that since their hands are warmer than the ice cubes, heat moves from their hand to the ice cube.

Melting

Explain to students that water is made up of tiny particles called “water molecules”. Normally, in liquid water, the water molecules are attracted to one another, are close together, but are able to move around and slide past each other. But when water is made cold enough, the water molecules slow down so much that their attractions hold them together and they can’t move past each other anymore. At this point they are still water molecules, but they are frozen into solid ice.

When heat is transferred from your hands to the ice, the water molecules start to move a little faster. If enough heat is transferred to the ice, the water molecules move enough that they break away from one another and start sliding past each other again. At this point, the solid ice has changed to liquid water. This process is called “melting”.

Activity 2 - Insulating an Ice Cube

1. Introduce the Activity

• Next, ask the students how they could do the opposite of what they did in the melting race. Ask students how they could prevent an ice cube from melting the longest. Introduce the term “insulation” and give real-world examples such as keeping cool air from air conditioning in the house, keeping coffee warm, or keeping ice cream cool if it is not in the freezer.
• Show students a second ice cube. Tell the students their job is to design an insulation device to keep the ice cube from melting for as long as possible.
• Give the students some time to examine the various insulating materials available for the activity and provide an opportunity to discuss what they think will work best. Students may do this individually or in small groups.
• Let students know that you will put an ice cube in a cup with no other insulation material. Explain that this sample with no insulation is the “control”. Students can compare their results to the results from the control to see if the insulation they added prevented the ice from melting as fast as it did with no insulation.
• Students should then choose which material they wish to work with. I allow students to pick only one type of material, so that we can have a better analysis of which materials work well as insulators. If necessary, assign materials so that not every student chooses the same material.
• You could conduct trials for materials that are not chosen, which can then be used for comparison purposes at the end of the lab.

Review Heat Transfer and Characteristics of Insulators

Most students can probably understand how heat is transferred from their hand to melt an ice cube.

But it may be more difficult for students to understand how heat is transferred from the air and surface the cup is on, through the cup and through the insulating material to melt the ice cube.

Explain to students that since the air, desk, cup, and insulating material are all warmer than the ice cube, heat will be transferred from all those materials to the ice cube.

Explain that the important characteristic about insulators is that they are not good at transferring heat. Certain substances like metal are good at transferring heat so they are not good insulators. But others, like cotton and air are not good at transferring heat, making them better insulators.

Procedure

1. Next, each student should be given a plastic cup to hold his or her device. Tell students that the device that they create needs to fit in the cup and that the cup will become part of the insulating device Since all groups use the same type of cup, the race is still fair. At this time, students should complete questions 1 and 2 on the student handout. Give the students approximately 20 minutes to create their insulated device.
2. Pass out ice cubes and place all the containers in the same location in the room. Check the ice cubes every five minutes. 
• In order to assess the progress of the ice cube, students must design a flap or access point where the ice cube can be viewed. Alternatively, there could be a set amount of time for the test, such as 20 minutes, or 30 minutes. After the time has completed, then students will check on the amount of melting that occurred.
• If students are checking on progress throughout the insulation test, use the opportunity to discuss which designs seem to be working well as insulation and which do not. 
• You could also use this time to discuss why insulation works to slow down the melting of the ice cube.
3. During the testing phase, have students sketch and label their design (question 3 on the student handout).
   • Depending on the level of your student group, you may also wish to have them measure the mass of their ice cube prior to starting the activity and again at the end of the test time period minutes. These measurements could be recorded in a table or graphed for data analysis. Teachers could also discuss the Law of Conservation of Mass in this instance.
   • Based on the results of the test, students should discover that designs that cover the entire cube work better than those with holes. Designs that allow for a layer of air between the insulation material and the ice cube also work better. Be sure to share the success of the various designs with the class. This should help students recognize which materials are more effective and offer evidence for their claim based on data from the activity. Have the students complete questions 4 and 5 on the student page.
4. Finally, as a class, have the students classify or group the materials as good insulators or poor insulators based on the results of the activity. Students should record this on their student handout.

Optional Extension/Suggested Follow-up Activity:

Using Vegetable Shortening as an Insulator

• This extension activity takes about 20 minutes and requires a large bowl of water with ice cubes, a large Ziploc bag, a small rubber glove and Crisco.
• Teacher directions:
  • Fill a large bowl with ice water.
  • Fill the large Ziploc with Crisco.
  • Place the smaller rubber glove on your own hand. Push your gloved hand into the middle of the Crisco, making a hand-sized impression inside the Crisco. The hand impression should be surrounded by Crisco!
  • When removing your hand, try to leave the rubber glove inside the Crisco-filled bag/inside the impression. The glove will act as a barrier to prevent student hands from getting greasy when they have the opportunity to investigate it.
  • Place the Ziploc bag containing the hand impression and Crisco in the large bowl of ice water. Arrange it so that water cannot get into the bag, but keep the bag open.
  • Next, allow students to place one hand inside the small glove, which is inside the hand mold of Crisco, in the bag, while placed in the ice water.
  • While students have one hand essentially surrounded by Crisco, ask them to place their other hand directly into the bowl of ice water.
  • Ask students if they notice a difference in the temperature of the water that they can feel between their two hands. Do not allow a student to leave their unprotected hand in the ice water for too long. Discuss.
  • Crisco is an excellent insulator because of its high density and low thermal conductivity. Encourage students to give examples of what animals may have natural insulation to protect from the cold.
  • Revisit the early question of how you can protect yourself from the cold. Ask the students how animals survive in very cold environments and discuss how blubber is an adaptation some animals use to protect themselves in very cold environments.