Making sense of changes
View Sequence overviewStudents will:
- work in teams to investigate the way specific variables affect the melting rate of chocolate.
- identify variables to change and keep the same in an investigation.
Students will represent their understanding as they:
- draw labelled diagrams to record their observations.
- present investigation results in a column graph.
- make claims based on evidence about their results.
In this lesson, assessment is formative.
Feedback might focus on:
- students’ fair-testing methods. With assistance, do they recognise the importance of changing only one variable and are they measuring and recording data accurately?
- students’ explanation of results. Do they use simple data to explain their findings?
Whole class
Class science journal (digital or hard-copy)
Demonstration copy of the Variables grid Resource sheet
Demonstration copy of the Melting investigation planner Resource sheet
Timing device (e.g. clock, stopwatch or iPad/phone with timer)
Heat source such as a heat pack, hairdryer, or using the sun
Each group
Chocolate (or other substance) for melting
2 resealable bags or paper plates to hold the chocolate
Texta/pen
Each student
Individual science journal (digital or hard-copy)
Melting investigation planner Resource sheet
Lesson
Re-orient
Review students’ predictions made in the previous lesson as to what might happen to materials such as metal, glass, plastic and chocolate when they are exposed to high temperatures.
Relating it to the discussion about testing hand sanitiser, discuss if it is possible and safe to test all of these substances in the classroom, and why or why not.
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkIdentifying and constructing questions is the creative driver of the inquiry process. It allows students to explore what they know and how they know it. During the Inquire phase of the LIA Framework, the Question routine allows for past activities to be reviewed and to set the scene for the investigation that students will undertake. The use of effective questioning techniques can influence students’ view and interpretation of upcoming content, open them to exploration and link to their current interests and science capital.
When designing a teaching sequence, it is important to spend some time considering the mindset of students at the start of each Inquire phase. What do you want students to be thinking about, what do they already know and what is the best way for them to approach the task? What might tap into their curiosity?
Read more about using the LIA FrameworkTo melt or not to melt?
Show students a piece of chocolate and ask them if they think it will melt, and how they might go about melting it.
Pose the broad question: What things might affect the time it takes for chocolate to melt?
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkThe Investigate routine provides students with an opportunity to explore the key ideas of science, to plan and conduct an investigation, and to gather and record data. The investigations are designed to systematically develop content knowledge and skills through increasingly complex processes of structured inquiry, guided inquiry and open inquiry approaches. Students are encouraged to process data to identify trends and patterns and link them to the real-world context of the teaching sequence.
When designing a teaching sequence, consider the diagnostic assessment (Launch phase) that identified the alternative conceptions that students held. Are there activities that challenge these ideas and provide openings for discussion? What content knowledge and skills do students need to be able to complete the final (Act phase) task? How could you systematically build these through the investigation routines? Are there opportunities to build students’ understanding and skills in the science inquiry processes through the successive investigations?
Read more about using the LIA FrameworkMelting investigation
Using the think-pair-share strategy, students brainstorm possible variables that will affect the melting time of chocolate.
Record these using the demonstration copy of the Variables grid Resource sheet, marking the measurable variable—the time it takes for chocolate to melt—in the centre of the grid with a bold M, and recording the other variables around it. You can add or remove columns/rows as required.
Determine which variable the students will test and write an investigable question using the question stem on the Variable grid Resource sheet.
For example, if you decide to change the dimensions of the chocolate, your investigable question might be What happens to the time it takes chocolate to melt when we change the dimensions of the piece of chocolate? (e.g. a full piece versus a broken-up piece). Alternatively, you might change the heat source itself, making your investigable question What happens to the time it takes chocolate to melt when we change the heat source used to melt it? (e.g. the sun versus a warm water bath).
If your students are not very experienced in carrying out fair tests, you might plan for all teams to change the same variable and carry out the same investigation. You could plan the investigation as a class using a demonstration copy of the Melting investigation planner Resource sheet. If your students are more experienced with fair testing you might allow them to select their own variable and plan the investigation themselves using their own copy of the Melting investigation planner Resource sheet.
During the planning of the investigation, determine how the time will be measured, and the most appropriate device and units to use. For example, the chocolate is unlikely to melt in seconds, so measuring in seconds using a stop watch would not be the best choice. The chocolate may take minutes or hours to melt, so a clock or timer might be more appropriate. Also determine how results will be recorded and displayed. A data table and column graph are included on the Melting investigation planner Resource sheet, however these can be modified for your students' needs.
Optional: Discuss fair-testing principles and why they are important.
In collaborative teams students plan and carry out their investigations, recording their results using the Melting investigation planner Resource sheet.
Using a variables grid to plan a fair test investigation
How might you support students to conduct an accurate fair test investigation, with a clear investigable question?
All scientific fair tests involve variables. Variables are things that can be changed (independent), measured/observed (dependent) or kept the same (controlled) in an investigation.
When planning a fair-test investigation, to make it a fair, we need to identify the variables. A variables grid can be used to record the identified variables. We then use these variables to turn a broad question, such as "What affects plant growth?" into an investigable one, such as "What happens to the growth of a plant when I change how much water it gets?".
Investigable questions are characterised by their clear identification of what is being changed and what outcome is being measured in a fair test, supporting students to investigate a specific physical phenomenon.
Investigable questions enable students to plan a fair test investigation. The question they have devised can be answered empirically, and data can be collected to support and justify claims made.
By planning for and conducting a fair test, students can make claims about how the variable they have changed in their investigation may have affected what is being measured and/or observed.
To support students to identify variables, and to use those variables to inform their planning of a fair test, we suggest this handy mnemonic ‘Cows Moo Softly’. This helps students remember the letters C, M and S, representing the three types of variables in a fair test:
- Cows: Change one thing (independent variable)
- Moo: Measure/Observe the outcome (dependent variable) and
- Softly: Keep the other things (controlled variables) the Same
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkFollowing an investigation, the Integrate routine provides time and space for data to be evaluated and insights to be synthesized. It reveals new insights, consolidates and refines representations, generalises context and broadens students’ perspectives. It allows student thinking to become visible and opens formative feedback opportunities. It may also lead to further questions being asked, allowing the Inquire phase to start again.
When designing a teaching sequence, consider the diagnostic assessment that was undertaken during the Launch phase. Consider if alternative conceptions could be used as a jumping off point to discussions. How could students represent their learning in a way that would support formative feedback opportunities? Could small summative assessment occur at different stages in the teaching sequence?
Read more about using the LIA FrameworkDiscussing results
In this Integrate step, guide students to link their experiences in the investigation to the science concept being explored—in this instance, that adding heat to some solids can cause them to become liquids. Through questioning and discussion, students should come to a consensus that:
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Teams share their investigation data with the class.
- Which pieces melted most quickly/least quickly?
- What did you notice about the times that it took the chocolate to melt?
- The faster it takes to melt, the less time will be recorded.
- What was different about the chocolate that melted fastest/slowest?
- What is happening when material melts?
- Where is the heat coming from?
- How does heat get into the chocolate?
- How do you know when the chocolate has completely melted?
Ask each team to make a claim to answer their original investigable question.
For example, if the original investigable question was What happens to the time it takes chocolate to melt when we change the dimensions of the piece of chocolate?, students should make a claim as to which sized pieces of chocolate melted first. If their original question was What happens to the time it takes chocolate to melt when we change the heat source used to melt it?, they should make a claim about which heat source melted the chocolate in the least amount of time.
Discuss students’ claims and consider the reason why they think they got the results they did. For example, if they tested smaller pieces of chocolate they might determine that their smaller sizes allowed heat to get into them more easily, or if they tested using different heat sources they might determine that one source was warmer than the other.
Discuss if students think that all solids can be changed from a solid to a liquid, and why they think that. You might focus on specific items in the classroom for discussion. Determine that not all solids can become liquids, even if you add a lot of heat. Instead, they might burn and become ash.
Review the investigation as a class and record students’ answers in the class science journal.
- What went well with our investigation?
- What didn’t go well? How could we have done it better?
- What ideas do you have for another investigation about the melting or freezing of materials?
Students draw a labelled diagram with an arrow to represent the transfer of heat from the heat source to the chocolate. They compare this to their original representation of the ice-monster melting created in Lesson 2, and make any changes or additions to that drawing in a different coloured pen/pencil.
Discuss with students how they might incorporate ideas about melting into their sensory experience and record their ideas in the class science journal.
Reflect on the lesson
You might:
- add to the class word wall any vocabulary related to melting rates and heat transfer.
- re-examine the intended learning goals for the lesson and consider how they were achieved.
- discuss how students were thinking and working like scientists during the lesson. Focus on fair tests, data collection, graphing or discussing results to interpret meaning.
Heat transfer
How is the heat conducted through the chocolate?
Conduction is a way heat is transferred from one object to another, or through an object. It occurs when heat travels through direct contact. In the sun, the warmer air particles have greater energy and pass their energy on to the particles on the surface of the chocolate. The outer chocolate particles gain energy and move faster, becoming a liquid. This transfer of energy continues from particle to particle through the chocolate until it gradually all melts and become a liquid.
Placing the chocolate on a hot metal surface causes the chocolate to melt faster, as metals are especially good at conduction. For example, if you put a metal spoon in a pot of hot soup, the spoon will soon feel hot because the heat is easily transferred through the metal.
Conduction is a way heat is transferred from one object to another, or through an object. It occurs when heat travels through direct contact. In the sun, the warmer air particles have greater energy and pass their energy on to the particles on the surface of the chocolate. The outer chocolate particles gain energy and move faster, becoming a liquid. This transfer of energy continues from particle to particle through the chocolate until it gradually all melts and become a liquid.
Placing the chocolate on a hot metal surface causes the chocolate to melt faster, as metals are especially good at conduction. For example, if you put a metal spoon in a pot of hot soup, the spoon will soon feel hot because the heat is easily transferred through the metal.