Lesson 2 - HOT SPOTS

Lesson 2 - HOT SPOTS

AT A GLANCE:

To provide students with hands-on, shared experiences of identifying heat sources in the classroom and at home.

Source: http://www.scootle.edu.au/ec/viewing/S7154/Heating-up-2013/lesson_2.html

Session 1 Hot or not?

Students:

identify heat sources in the classroom
identify primary and secondary heat sources
record observations in a table.

Session 2 Heat at home:

Students:

identify primary and secondary heat sources at home
take a photo or draw a heat source and bring to school.

Lesson focus

The Explore phase is designed to provide students with hands-on experiences of the science phenomenon. Students explore ideas, collect evidence, discuss their observations and keep records, such as science journal entries.
The Explore phase ensures all students have a shared experience that can be discussed and explained in the Explain phase.

Assessment focus

Formative assessment is an ongoing aspect of the Explore phase. It involves monitoring students’ developing understanding and giving feedback that extends their learning. In this lesson you will monitor students’ developing understanding of:

how heat can be produced in many ways.

Key lesson outcomes

Science

Students will be able to:

identify heat sources in the classroom
sort heat sources into heat producers and things heated by heat producers
identify heat sources at home.

Given a hierarchy of things that are important to know about heat, the above exercises focus on some of the most ambiguous and useless. The lesson outcomes are more likely to reinforce the existing misconceptions of both students and teachers than to promote scientific understanding.

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CONFUSED DIFFERENTIATION OF PRIMARY vs SECONDARY SOURCES: The prescribed PrimaryConnections activities are more about semantics than physics. The supplied examples (including 'objects such as computers, electrical stove elements, toasters, hair dryers or light bulbs' are at best, confusing: For example, a computer is given as an example of a 'heat producer' rather than an object 'heated by something else'. This example is ambiguous at best and arguably false: When a computer is turned 'off' it does not produce heat - it only produces heat when turned 'on'.. and any all resulting 'heat' is the bit left over as a result of unwanted inefficiency. A computer that did its job perfectly efficiently would not produce any heat. Similar ambiguities apply to other common examples. The supplied examples do more harm than good by promoting the existing misconceptions both of teachers and students).

In the 19th century, heat was understood in the context of 'caloric theory'. According to caloric theory, heat was material in nature. It was a physical substance - a fluid that could flow from one object to another. In the modern scientific view, heat is not something contained in an object; rather it is something transferred between objects. The heat no longer exists when the transfer ceases.

BETTER DIFFERENTIATION OF PRIMARY vs SECONDARY SOURCES: Students firstly need to have their attention drawn to a distinction between 'heat' and 'energy' in the context of scientific language. In general, all the energy available on our planet derives, directly or indirectly, from the Sun: water energy, wind energy, chemical energy of fossil fuels (coal, oil and natural gas) and biomass (i.e. wood); even waves energy. Tidal energy derives from the gravitational fields of the Sun, Moon and Earth. Geothermal and nuclear energy do not derive from the subsequent transformations of solar energy, but are related to the Earth formation. Source:Eniscuola

In case identification and classification of heat sources was though to be important, then why not focus on higher order, more generalisable concepts: Better to focus on solar, geothermal and nuclear rather than candle wicks and hot water bottles!

By shifting focus to solar, geothermal and nuclear, primary sources, students can learn that these sources can be used directly, as they appear in the natural environment: coal, oil, natural gas and wood, nuclear fuels (uranium), the sun, the wind, tides, mountain lakes, the rivers (from which hydroelectric energy can be obtained) and the Earth heat that supplies geothermal energy.

Secondary sources derive from the transformation of primary energy sources: for example petrol, that derives from the treatment of crude oil and electric energy, obtained from the conversion of mechanical energy (hydroelectric plants, Aeolian plants), chemical plants (thermoelectric), or nuclear (nuclear plants). Electric energy is produced by electric plants, i.e. suitable installations that can transform primary energy (non-transformed) into electric energy.

Also , to correctly understand the modern scientific view, students need to understand that heat is present only when there is an energy transfer. When comparing two objects, it is senseless to speak of heat as still existing once the two objects have come to thermal equilibrium. Heat is not something contained in an object; rather it is something transferred between objects. The heat no longer exists when the transfer ceases. Students also need to be able to better differentiate 'heat' and 'energy', but let's leave that for another day. Source: http://www.physicsclassroom.com/class/thermalP/Lesson-1/What-is-Heat|

In any case, although explained correctly in 'teacher background information' (below), most teachers would not be able to guide students in gaining correct scientific understanding of the given examples, so better to find less ambiguous activities to replace the above:

The current PrimaryConnections explanation(s) is/are not well reinforced/consolidated by the prescribed activities

Literacy

Students will be able to:

understand the purpose and features of a table and T-chart
use oral, written and visual language to record and discuss their observations of heat sources
engage in discussion to compare ideas about heat sources.

This lesson also provides opportunities to monitor the development of students’ general capabilities.

Teacher background information

Heat sources

Whether or not something is a ‘source’ of heat depends on its surroundings. If a material is put in contact with a colder material whose atoms move more slowly then heat transfer will occur until both materials reach the same temperature.

Primary heat sources are heat sources that produce their own heat (see below for examples).

A secondary heat source is something that is heated by a primary source and then transmits the heat to something colder, for example, a hot water bottle is a secondary heat source for warming the bed.

Producing heat

Some examples of how heat can be produced are:

Electrical energy is converted into thermal energy (heat) when you use objects such as computers, electrical stove elements, toasters, hair dryers or light bulbs.
Movement energy (kinetic) from friction creates heat. For example, rubbing your hands, sharpening a pencil, spinning skateboard wheels.
Chemical energy including burning. For example, foods we eat are converted into heat in our bodies; fire, candles and gas heaters burn to produce heat.
Light from the sun is converted to heat as the sun's rays warm the earth's surface.

For clarification see: how heat is radiated from the sun

Students’ conceptions

When looking for heat sources, students might be confused by their body heat and identify things such as books as being warm. This might also arise from a confusion of what ‘warm’ means. Encourage students to identify whether things are actually warming their hand and ask the whole team to check whether they agree.

Students might think the wick of a candle is burning, however it is the wax vapour which burns to form the majority of the flame we see. The wick does burn, but its main purpose is to provide a way for the wax to get hot enough to vaporise and burn.

The candle/wick example is very 'nineteenth century'. Candles and the way they burn are no longer something that students, teachers and parents engage with on a day-to-day basis. Thus, the relationship between 'burning', 'wax vapour' and 'wick' are unlikely to be generally well understood. A burning candle in the classroom is also a potential hazard - There are alternative activities that would provide significantly better and safer education outcomes.

Students might think that the Earth gets heat by thermal radiation from the Sun. The Sun is actually too far from the Earth to heat it directly. Instead, the light from the Sun is reflected or absorbed by objects on Earth. Absorbed light usually increases the energy in an object, causing the object to heat up.

Most people (including teachers) may also believe that “the Earth gets heat by thermal radiation from the Sun”. Also, the proposition that “The Sun is actually too far from the Earth to heat it directly” may also not be generally understood - Potentially lots of confusion around understanding of 'radiation' and 'too far'.

Some students might think that materials are intrinsically warm (blankets) or cold (metals). They might think that objects that keep things warm (such as a sweater or gloves), may be thought to be sources of heat instead of the objects keeping things warm by trapping heat.

Session 1 Hot or not

Equipment

FOR THE CLASS

class science journal
word wall
team roles chart
team skills chart
1 enlarged copy of ‘What’s hot?’ (Resource sheet 1)
candle
hot water bottle
kettle containing warm water
collection of heat sources or pictures of them (see ‘Preparation’)

FOR EACH TEAM

role wristbands or badges for Director, Manager and Speaker
each team member’s science journal
1 copy of ‘What’s hot?’
(Resource sheet 1) per team member

Preparation

Read ‘How to organise collaborative learning teams (Year 3–Year 6)’ (Appendix 1). Display an enlarged copy of the team skills chart and the team roles chart in the classroom. Prepare role wristbands or badges.

Prepare an enlarged copy of ‘What’s hot?’ (Resource sheet 1).

Collect other heat sources, or pictures of them, for students to explore in the classroom, such as a hair-dryer, curling wand, computer, clock/radio, warm cup of tea.

Optional:

Do ANY activities below provide relative value in promoting understanding of heat?

Display the pictures of heat sources and ‘What’s hot?’ (Resource sheet 1) on an interactive whiteboard. Check the PrimaryConnections website to see if an accompanying interactive resource has been developed (www.primaryconnections.org.au [Opens new Window]).

Prepare a class T-chart with the column headings ‘Heat producers’, and ‘Heated by something else’. Leave space for a title at the top of the sheet (see Lesson steps 9 and 11).

Lesson steps

Review the previous lesson using the class science journal. Using the ideas map, review things that students identified as those to stand next to when trying to warm up.

Explain that students will be working in collaborative learning teams to see how many different things they can find in the classroom that feel warm or hot. Discuss how to identify if things are warm or hot, for example, by feeling if they are warm to touch.

Optional: Allow teams to investigate more areas than just the classroom.

Safety: Discuss safe ways of searching for heat sources, including slowly moving a hand towards something, and withdrawing before it gets too hot.

Introduce the enlarged copy of ‘What’s hot?’ (Resource sheet 1). Read through and discuss. Discuss the purpose and features of a table.

Literacy focus

Why do we use a table?

We use a table to organise information so that we can understand it more easily.

What does a table include?

A table includes a title, columns with headings and information organised under each heading.

Model how to complete the table using a candle. Write ‘candle’ in the first column.

In a primary classroom environment, is it a good idea to experiment with flames/burning candles and/or water, ice blocks and similar hazards (unless no safer/better option is available)?

Ask students to touch the candle. Ask questions, such as:

Did you expect it to be hot? Why/Why not?
What does it need in order to be hot? Why?
Light the candle and complete the rest of the columns. Safety

Safety note: Remind students to slowly move their hands towards the candle and move their hands away when it becomes too hot.

Discuss the last column ‘Produces its own heat? Or heated by something else?’

Ask students:

Is the candle producing its own heat or is it heated by something else? (Producing its own heat.) How do you know? (I can see it burning.)

- Again, does this 'candle' activity and the given explanation make any sense or assist student understanding? There are more easily understood and safer teaching activities to achieve the same or better outcomes.

Model how to complete the last column for a candle.

Show students the cold hot water bottle. Discuss what it is and what it is used for. Pour warm water from a kettle into the hot water bottle. Ask students to feel the heat of it. Ask students:

Is the hot water bottle producing its own heat or is it heated by something else? (Heated by something else.)
How do you know? (The hot water in it was heated by a kettle.)
Discuss how students will form teams to complete an entry on their resource sheet for the hot water bottle and other items in the classroom.
Personal and social competenceForm teams and allocate roles. Ask Managers to collect team equipment. If students are using collaborative learning teams for the first time, introduce and explain the team skills chart and the team roles chart. Explain that students will use role wristbands or badges to help them (and you) know which role each member has.

Allow time for teams to complete the activity.

Work sample of ‘What’s hot?’ (Resource sheet 1)

Explain that teams will share their findings as a class using a T-chart. Introduce the T-chart (see ‘Preparation’) and discuss its purpose and features.

Literacy focus

Why do we use a table?

We use a table to organise information so that we can understand it more easily.

What does a table include?

A table includes a title, columns with headings and information organised under each heading.

Ask Speakers to share their team’s findings. List warm or hot objects found by teams on self-adhesive notes and ask the Speakers to place it in the column on the T-chart that matches their findings. Encourage dialogue by asking questions, such as:

Who agrees with what this team found? Why?
Who disagrees with what this team found? Why?
Write the title ‘Heat sources in our classroom’ above the T-chart and ask students what they think a ‘heat source’ is. Discuss how it is something that gives heat to other things and that all of these things are heat sources.

Heat sources in our classroom

Critical and creative thinking

Read through the heat producers’ side of the T-chart and ask questions, such as:

What other heat producers can you think of?
Is there anything similar about any of the heat producers?

Formative assessment

Read through the heat producers’ side of the T-chart and ask questions, such as:

Revise the ‘Our questions about heat’ page in the class science journal.
Add any new questions that students might have.
Update the word wall with words and images.

Resource sheet 1

Resource sheet 1 - What's hot?

Equipment

FOR THE CLASS

class science journal
word wall
‘Heat collection’ board
1 enlarged copy of ‘Information note for families’ (Resource sheet 2)

FOR EACH STUDENT

student science journal
1 copy of ‘Information note for families’ (Resource sheet 2)

Again, for reasons detailed above, the following exercises (and the contents of their associated 'resource sheets') are at best deeply ambiguous. The categorisation of 'heat sources' of this type do not clearly explain or reinforce modern scientific understanding about heat transfer - and in any case, such data records have no intrinsic value without some more meaningful prescribed activity/analysis that depends upon them?

Preparation

Set up a ‘Heat collection’ board for the students to place their photos or pictures of heat sources brought from home. Use a T-chart format as in Session 1 with the title ‘Heat sources at home’, and the columns ‘Heat producers’ and ‘Heated by something else’.

Prepare an enlarged copy of ‘Information note for families’ (Resource sheet 2).

Lesson steps

Review the previous lesson using the class science journal and T-chart. Discuss objects and activities that were warm, hot or very hot to touch.

Explain to students that they will be looking for heat sources at home. Ask students to find an object at home that is a heat source and either take a photo or draw a picture of it. Discuss examples of what they might find. Examples include a hairdryer, curling wand, matches, stove element, gas burners, hot water system, television, electric blanket, oven, clock/radio or printer.

Introduce the enlarged copy of ‘Information note for families’ (Resource sheet 2) and discuss the ‘Tasks to do’ section.

Safety: Remind students of safe ways of searching for heat sources, including slowly moving a hand towards something, and withdrawing before it gets too hot.

Show students the ‘Heat collection’ board where their photos and drawings will be placed for discussion in the next lesson.
Distribute ‘Information note for families’ (Resource sheet 2) to students.
Update the word wall with words and images.

Curriculum links

Science: Further investigate and compare different ways heat can be produced.

Mathematics: Create a graph of how many heat sources were found in different locations.

Resource Sheet 2

Click to download the resource sheet - also see information note for families

Table of Contents

Lesson 2 - HOT SPOTS

AT A GLANCE:

Session 1 Hot or not?

Session 2 Heat at home:

Lesson focus

Assessment focus

Key lesson outcomes

Science

Literacy

Teacher background information

Heat sources

Producing heat

Students’ conceptions

Session 1 Hot or not

Preparation

Optional:

Lesson steps

Literacy focus

Literacy focus

Personal and social competence / Formative assessment

Heat sources in our classroom

Critical and creative thinking

Formative assessment

Resource sheet 1

Resource sheet 1 - What's hot?

Preparation

Lesson steps

Curriculum links

Resource Sheet 2