Making sense of changes
View Sequence overviewStudents will:
- generate and investigate questions to decide whether the mystery substance is a solid or liquid.
- investigate and observe the mystery substance and use the findings as evidence to make a claim about whether it is a solid or a liquid.
- explore how candy changes states from liquid to solid during production, and at times it can be difficult to categorise.
Students will represent their understanding as they:
- pose questions to differentiate solids from liquids.
- write and draw observations.
- support their claim with evidence from their investigations.
- discuss changes that occur during the candy making process from liquid to solid, and recognise that sometimes candy has properties of both.
In this lesson, assessment is summative.
Students working at the achievement standard should have:
- identified solids and liquids and named the properties of each.
- identified that solids and liquids can change states by adding/removing heat.
They might also have:
- communicated their science understanding effectively by generating reasonable questions and a claim with evidence to differentiate between solids and liquids.
Refer to the Australian Curriculum content links on the Our design decisions tab for further information.
Whole class
Class science journal (digital or hard-copy)
A mystery substance, contained within a box, which is able to be divided into smaller pieces. Select a substance that has some of the properties of a solid and some of the properties of a liquid, for example: modelling clay, sponges, oobleck, or a pourable solid such as sugar, flour, washing powder. See the embedded professional learning on Adapting to your context—Mystery substances below for further guidance on selecting your substance.
Video: How hard candy is made (13:21)
Optional: Some hard candy to share with the class (be aware of potential food allergies)
Optional: A second mystery substance to compare to the first
Each group
What is the mystery stuff? Resource sheet
A small amount of mystery substance
2 clear cups or jars to attempt to pour the substance and to observe whether it levels out on its own
Each student
Individual science journal (digital or hard-copy)
Lesson
Re-orient
Use the class science journal to recall the properties, determined over the course of the sequence, that make a material a solid or a liquid. You might review:
- students’ original ideas recorded in Lesson 1.
- the Venn diagram created in Lesson 2.
- how liquids can change viscosity by adding/removing heat, as explored in Lesson 3.
- how many liquids freeze and turn into solids when enough heat is removed, as explored in Lesson 4.
- how some solids melt and turn into liquids when enough heat is added, as explored in Lesson 5.
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 FrameworkSolid or liquid?
Show students a box containing a mystery substance and explain that their task is to investigate to find out if it is a substance is a solid or a liquid.
Pose the question: What investigations might we carry out to determine if this substance is a solid or a liquid?
Adapting to your context—Mystery substances
What mystery substance might you select for this lesson?
In this lesson students have the opportunity to apply their learning about solids and liquids by identifying tests they might carry out to determine if a mystery substance is a solid or a liquid.
The mystery substance should be a bit challenging to classify as a solid or a liquid and safe for students to handle and investigate. It should have some of the properties of a solid and some of the properties of a liquid. The unknown substance will encourage students to articulate individual properties and to identify if the substance is ‘more like a liquid or a solid’.
In this sequence, students have established that:
- solids do not change their shape easily, but some can be changed by adding or removing heat energy.
- liquids do change shape easily, and take the shape of the container they’re in. This can also be changed by adding and removing heat energy.
- pourable solids can act a bit like liquids, but they are not. We can determine this by seeing if they ‘mound’ when poured, or if they level out on their own.
- adding heat energy turns some solids into a liquid. Removing heat energy turns some liquids into a solid.
When selecting your mystery substance/s, select substances which seem to ‘break’ one or more of these rules.
For example:
- Playdough is a mixture of solids (starch and gluten) suspended in a liquid (usually water). It can be molded and changes its shape easily, although it does not flow like a liquid. Adding heat energy to playdough, by baking it for example, will make it more solid, not less (which is what students might expect based on what they've learned in the sequence). Playdough is versatile, and can be a valuable addition to a school’s science resources. It can be purchased or made. It is used in other Primary Connections teaching sequences including Take, shape and create (Year 2) and Finding features (Foundation). You'll find a recipe for homemade playdough in the Preparing for this sequence tab of Take, shape and create.
- Clay consists of solid particles, but when mixed with water it can also be molded and made to change its shape easily. When it is mixed with a lot of water, it can even seem to behave like a liquid, as it can ‘flow’. In this case however, what has been created is a suspension—solid particles that have not dissolved, floating in water. It is the water that is ‘flowing’, not the clay itself. Like playdough, adding heat energy will make it more solid, as the liquid is removed through evaporation.
- Toothpaste is considered a semi-solid (or non-Newtonian fluid), as it is not a true solid or a pure liquid. Instead, it is a mixture of particles such as sodium fluoride and hydrated silica in water. When undisturbed, it has a high viscosity and will hold its shape. When force is applied, its viscosity decreases and it will flow.
- Oobleck (made using a 2:1 ratio of cornflour to water) is another non-Newtonian fluid and safe to handle. It will be explored again if teaching the Communicating matters (Year 5), so is a good option to use here to set students up for success in future years. See the Launch step of Lesson 1 of Communicating matters for more details about oobleck.
In this lesson students have the opportunity to apply their learning about solids and liquids by identifying tests they might carry out to determine if a mystery substance is a solid or a liquid.
The mystery substance should be a bit challenging to classify as a solid or a liquid and safe for students to handle and investigate. It should have some of the properties of a solid and some of the properties of a liquid. The unknown substance will encourage students to articulate individual properties and to identify if the substance is ‘more like a liquid or a solid’.
In this sequence, students have established that:
- solids do not change their shape easily, but some can be changed by adding or removing heat energy.
- liquids do change shape easily, and take the shape of the container they’re in. This can also be changed by adding and removing heat energy.
- pourable solids can act a bit like liquids, but they are not. We can determine this by seeing if they ‘mound’ when poured, or if they level out on their own.
- adding heat energy turns some solids into a liquid. Removing heat energy turns some liquids into a solid.
When selecting your mystery substance/s, select substances which seem to ‘break’ one or more of these rules.
For example:
- Playdough is a mixture of solids (starch and gluten) suspended in a liquid (usually water). It can be molded and changes its shape easily, although it does not flow like a liquid. Adding heat energy to playdough, by baking it for example, will make it more solid, not less (which is what students might expect based on what they've learned in the sequence). Playdough is versatile, and can be a valuable addition to a school’s science resources. It can be purchased or made. It is used in other Primary Connections teaching sequences including Take, shape and create (Year 2) and Finding features (Foundation). You'll find a recipe for homemade playdough in the Preparing for this sequence tab of Take, shape and create.
- Clay consists of solid particles, but when mixed with water it can also be molded and made to change its shape easily. When it is mixed with a lot of water, it can even seem to behave like a liquid, as it can ‘flow’. In this case however, what has been created is a suspension—solid particles that have not dissolved, floating in water. It is the water that is ‘flowing’, not the clay itself. Like playdough, adding heat energy will make it more solid, as the liquid is removed through evaporation.
- Toothpaste is considered a semi-solid (or non-Newtonian fluid), as it is not a true solid or a pure liquid. Instead, it is a mixture of particles such as sodium fluoride and hydrated silica in water. When undisturbed, it has a high viscosity and will hold its shape. When force is applied, its viscosity decreases and it will flow.
- Oobleck (made using a 2:1 ratio of cornflour to water) is another non-Newtonian fluid and safe to handle. It will be explored again if teaching the Communicating matters (Year 5), so is a good option to use here to set students up for success in future years. See the Launch step of Lesson 1 of Communicating matters for more details about oobleck.
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 FrameworkGenerating questions and testing
In collaborative teams students brainstorm as many questions as they can think of that might help them determine if the mystery substance is a solid or a liquid. If required, prompt their thinking with some examples such as:
- Does it hold its shape?
- Can it change shape?
- Does it pour?
Record the teams’ questions in a table. Discuss and record how each question might be tested, and how useful and reliable the answer might be.
Give each team a sample of the mystery substance and ask them to carry out their testing ideas and record the results in a table.
You might design an appropriate data table together as a class, or allow students to design their own.
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 FrameworkWhat is it?
In this Integrate step, guide students to link their experiences in the investigation to the science concept being explored—in this instance, that solids and liquids have observable properties. Through questioning and discussion, students should come to a consensus that:
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Invite teams to make a claim whether the mystery substance is a solid or a liquid and to support their claim with evidence from their investigation.
Reveal to students whether the mystery substance is a solid or a liquid, and explain why. For example, for playdough: Some materials are difficult to classify as either a solid or a liquid. Playdough is actually a solid, but it's a special kind called a ‘viscoelastic solid’. That means:
- it has both viscous and elastic properties.
- it can change shape easily when you push or pull it.
- it doesn’t flow or pour like a liquid. So, even though it feels squishy, it still holds its shape and doesn’t spread out on its own.
The science of candy making
Connect these ideas to candy making, as another example of substances that are difficult to classify: Often during food production, when heat is added or removed, the substance changes between liquid and solid, and at times it can be difficult to decide which one it is. This can be seen during the candy making process.
View How hard candy is made (13:21). You may choose to:
- pause along the way for students to apply their knowledge and decide whether the candy is in a solid state or liquid state.
- stop the video at 4:35 (the end of the candy cane making process), or continue the video for students to see more changes of state and how drop candies and blackpool rock/image candies are made.
Discuss what changes occurred to the candy by adding/removing heat.
- Did the stove add or remove heat? While it was hot, was it solid or liquid?
- When the candy is hot, it is liquid.
- When the candy poured onto the bench, did the bench add or remove heat from the candy?
- The bench was cold, so it removed heat—the heat transferred away from the candy and into the bench.
- Why is it important for the candy to go through a state of being not quite a solid and not quite a liquid?
- It allows the candy to be shaped, twisted, and rolled while it slowly hardens.
Add candy to the chart from Lesson 4, to show whether candy is a solid or liquid at freezer, fridge, room, and warmer temperatures. Students will need to use their knowledge and experiences to make claims about the state of candy for fridge and freezer columns.
Discuss how students might use what they have learned when designing their sensory experience.
Optional:
- Share some hard candy with the class to eat.
- Compare the first mystery substance to a second mystery substance.
Collect the mystery substance for use again next lesson.
Reflect on the lesson
You might:
- place a piece of candy in the fridge and freezer to confirm whether the students’ claims for cooler temperatures are correct.
- invite students to share their ideas on other substances that might be difficult to classify, such as hair gel, toothpaste and shaving cream.
- add to the class word wall any vocabulary related to solids, liquids and changing states.