Baked Alaska

Baked Alaska

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about using science ideas, pictures and models to understand how a recipe for Baked Alaska works.

Question 1Change answer

 
a)  Why doesn't the ice cream melt while it is in the oven?

Question 2Change answer

b)  Why can't you make baked Alaska and keep it for later?

Question 1Change answer

A chilly bin is used to keep food and drinks cold when you go on a summer picnic. Mary says that the chilly bin is like a baked Alaska. She draws diagrams of the baked Alaska and the chilly bin to show how they would look if you could cut a slice from each of them.

Baked Alaska                                                        Chilly bin
c)  The meringue and the sponge are like the chilly bin. Explain how.
Task administration: 
This task can be completed with pencil and paper or online.
Copyright: 
Permission for use granted.
Images: Kerry Parker (NZCER)
Levels:
3, 4, 5
Curriculum info: 
Science, Communicating in science, Material World
Keywords: 
chemistry and society, insulation, heat, analogies, diagrams, interpreting diagrams, science capabilities
Description of task: 
Use knowledge of insulation to answer questions about baked Alaska dessert, and how it compares to a chilly bin. Assessment focus: Interpreting diagrams, interpreting analogies, and using knowledge of insulation.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Interpret representations
This resource provides opportunities to discuss what a model shows, and how it is the same and different from the real thing.
 
Science capabilities: 
Interpret representations
Answers/responses: 
    Y6 (03/2010) Y8 (03/2010) Y10 (03/2010)
a) The ice cream is insulated by the meringue
or
The heat is kept out/ the cold is kept in
Partial answer: the meringue is covering the ice cream (refer to Working with students)		 very difficult very difficult difficult
b) The ice cream will go from frozen to room temperature
or
The ice cream will melt		 difficult moderate easy
c) The layers are insulators which stop the heat from getting to the ice cream (best answer).
or
Keep the heat out/keep the cold in.
very difficult
 

difficult
very difficult
 

difficult
difficult
 

moderate

Based on a representative sample of 112 Year 6, 143 Year 8 and 299 Year 10 students.

Teaching and learning: 
Background information

Being scientifically literate requires the ability to read texts. Students need to be able to analyse and interpret a range of text types, including diagrams. Diagrams are used widely in science to explain abstract ideas, show a particular detail, or describe a process.
Analogies are another common way of communicating in science. They involve comparison of two things that are similar in some respects. Scientists use familiar contexts to explain abstract or unfamiliar science concepts.
Insulation to keep things cool or warm has many useful applications in our daily lives, from keeping the ice cream from melting before we get home from shopping to keeping our houses warm. Baked Alaska is an everyday, although for many students unfamiliar, example of insulation in action. It provides an engaging context for investigating students' understanding of this concept.
The key ideas that are covered in the task are shown in the table below. 
 
Nature of science idea Science knowledge
  • Diagrams are one way of showing science ideas.
  • Scientists use analogies to explain science concepts. An analogy compares two things that have something in common.
  • Some everyday materials act as insulators, slowing down the movement of heat.
 
Nature of science: Communicating in science (tables)

Flow charts: Questions a) and b)
A lot of the younger students did not answer the questions. Some gave us feedback that they were not familiar with the Baked Alaska dessert and gave this as a reason for not giving an explanation.
As the information they needed was in the flow chart, this suggests that they either did not attend to all the details of the diagram, or they could not understand what it showed. Other possibilities are that they were having difficulty explaining their ideas or could not transfer their experiences of insulation to an unfamiliar context.
Next steps
Ask questions that help students attend to the different parts of a flow chart:

  • What do the photographs tell us?
  • What does the written text tell us?
  • What do the arrows mean?

Ask questions that help students connect what they know about insulation in other contexts:

  • What do you do after you after you put ice cream and then fluffy meringue on top of the cake and jam?
  • Can you think of other ways we can keep ice cream from melting?
  • Do you think you could use something else to cover the ice cream in the baked Alaska? What do you think would work and why? What do you think would not work and why?
Analogies: question c)
Very few younger students wrote about the layers of both the chilly bin and the Baked Alaska acting as insulators that keep the heat out but by Year 10 nearly a fifth of students did.

"The meringue and sponge act in the same way as the plastic foam as they prevent the conduction of heat inside. These are thermal insulators to prevent heat from entering." Year 10

However, some students recognised the similarity in the function of the two items.

Response to c)

Year 6

Year 8

Year 10

Keeps the heat out/keeps the cold in

About a fifth

About a third

About a third
Based on a representative sample of 112 Year 6, 143 Year 8 and 229 Year 10 students

Others compared the physical properties of the layers without explaining how they were alike. The plastic foam is like the sponge on the cake. Year 8

Next steps

A strategy for helping students unpack analogies is:

The strategy     Baked Alaska/chilly bin example
Introduce the target concept Keeping the heat out (insulation)
Identify relevant features
 The meringue is like the lid and sides
The sponge cake is like the bottom.
Connect the similar features
 The meringue/ sponge cake and the plastic foam encase the material that is to be kept cold.
Indicate where the analogy breaks down You cannot cook the chilly bin.
It is hotter in the oven than room temperature. The heat will affect the ice cream more quickly than in the chilly bin.
Draw conclusions about the target concept The chilly bin and the baked Alaska slow down the heat getting to the contents inside.
Adapted from Glynn, 2004
 
 
Science concept: Insulation

In question a) about half of the younger (Year 6 and Year 8) students identified the covering of meringue stopped the ice cream from melting.

Response to a) Year 6 Year 8 Year 10
Covering (stops the ice cream from melting) About half About half About half
Based on a representative sample of 112 year 6, 143 year 8 and 299 year 10 students

About a tenth of these Year 6 and Year 8 students included an explanation that the meringue kept the heat out or the cold in. These responses demonstrate the beginnings of ideas about insulating materials.

  • Between the fluffy meringue the coldness cannot be harmed. Year 6
  • The fluffy meringue is protecting it. Year 8
  • Because it is protected by meringue and there are no holes for the hot air to enter Year 8

By Year 10 nearly a fifth of students could identify and explain that the meringue was acting as an insulator.

  • Because the heat is not conducted through the meringue and sponge cake Year 10
  • Because the aerated egg white acts as insulation and keeps the heat out Year 10

Some students explained why the ice cream didn't melt by applying the concept of time:

  • Because the Baked Alaska is being cooked at a high temperature. The outside gets cooked quickly while the heat doesn't reach the inside Year 10
  • Because the Baked Alaskas are left in the oven for just enough time to turn golden brown on the outside and not melt the ice cream on the inside Year 8
  • ... if it was in for longer it might have melted. Year 8

While we didn't credit these answers as correct because we were specifically looking for evidence of understanding about insulation, time is indeed a factor, and students should not be told they are wrong. These responses would make good discussion starters.

Misconceptions

Some students thought that the air pockets in the meringue were a sponge for the heat (soaking up the hot air) rather than the air in the air pockets being a poor conductor of heat. Examples from Year 10 students include:

  • The meringue expands absorbing all of the heat.
  • The other ingredients absorb the heat before it reaches the ice cream.
  • As heat comes through the meringue the sponge absorbs the heat and protects the ice cream.

In question b) some students focussed on aspects of long term changes instead of linking the design of the cake to insulation. This was most common with younger students.

Response to b) Year 6 Year 8 Year 10
When the cake is cold it is not nice to eat/it will go rotten. About a third About a sixth About an eighth
Based on a representative sample of 112 Year 6, 143 Year 8 and 229 Year 10 students

Next steps

To help students to understand the properties of insulators and what type of materials make good insulators teachers could encourage them to discuss why they think the meringue stops the ice cream from melting. To support the discussion, questions could include:

  • Describe what meringue looks like/ the properties of meringue.
  • What properties of meringue do you think might stop the heat getting through to the ice cream/ make it a good insulator? Why do you think that?
  • If you could take the temperature of the meringue that lies next to the ice cream, do you predict that the temperature would be warmer or cooler than the outside of the meringue? Warmer or cooler than the ice cream? Give reasons. (look for reasons that indicate understanding of insulation, as opposed to proximity to heat or cold, although this may have some bearing on the temperatures too).
  • What insulators do we know about? Is there anything similar about them and meringue?
To further explore their thinking students could test their ideas by planning and carrying out investigations for their questions or researching and linking the information to this context.
Communicating in science

For another ARB resource about analogies see Investigating the water cycle.

For further ideas for focussing on Communicating in science see the science capability Interpret Representations

Insulation

The following books have many investigations about insulation and movement of heat. They also provide clear background notes for teachers.
  • Ministry of Education (2001). Building Science Concepts Book 14, Making Porridge. Wellington: Learning Media.
  • Ministry of Education (2003). Building Science Concepts Book 36, Heat on the Move and Book 47 Insulation. Wellington: Learning Media.
  • Ministry of Education (2010). Connected 1.Wellington:Learning Media: Staying Warm Keeping Cool. (See also Teachers' Notes )
  • Ministry of Education (1999). Making Better Sense of the Physical World. Wellington: Learning Media. Refer to the section, Heat.
An activity about insulation can be found on the Science Online website.