Light imitates art
View Sequence overviewStudents will:
- plan, conduct and analyse the data collected in a fair-test investigation.
- make claims about how the proximity of a light source can affect the height of a shadow.
- make generalisations about other ways they might change the size and shape of shadows.
Students will represent their understanding as they:
- use equipment to measure and record their data.
- construct and use ray diagrams, and tables to describe the change in shadow length.
- communicate their understanding of their fair test investigation.
In this lesson, assessment is summative.
Students working at the achievement standard (science inquiry) should have:
- posed an investigable question.
- planned and conducted a repeatable investigation to answer this question.
- used equipment to observe, measure and record data with reasonable precision.
- constructed appropriate representations of this data, including a data table and graph.
- analysed the data to identify patterns.
- made a claim based on the data/evidence to answer their question.
- communicated their claim/s and evidence clearly.
- compared their methods and findings with others, determining sources of possible error, and where their claims correlate with those of others.
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)
Materials to create a word wall
Demonstration copy of the Variables grid Resource sheet
Demonstration copy of the Shadow height investigation planner Resource sheet
Each group
Grid paper marked at 0.5cm (preferably) or 1cm intervals to use as a measurement screen to measure the height of the shadow
OR
Ruler or tape measure, to measure the height of the shadow, if the measurement screen above is not provided
An easily moveable small object that will cast a defined shadow, for example a glue stick
Torch
Ruler or tape measure, to measure the distance of the object from where the first shadow is cast, and the increasing/decreasing 5cm intervals before casting a new shadow
Each student
Individual science journal (digital or hard-copy)
Shadow height investigation planner Resource sheet
Lesson
Re-orient
Review the previous lessons and discuss what students have learned about shadows.
- What is a shadow?
- How can you make a shadow?
- Why do shadows change in size?
- Are shadows always the same size as the object that makes them? Why or why not?
- Why can’t you see your face in a shadow?
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 FrameworkShadow shapes
Pose the question: How can I make a shadow taller? Shorter? Wider? Thinner?
Brainstorm student ideas and record them in the class science journal.
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 FrameworkChanging shadows
Explain that in this investigation students will investigate what things affect the height of a shadow, and use the evidence they collect to make generalisations about how they can change the size and shape of a shadow.
Starting with the broad question “What things might affect the height of a shadow?” brainstorm potential variables using the Variables grid Resource sheet. Some examples of potential variables are:
- the distance from the light source to the object.
- the distance from the object to anything behind it.
- the angle of the torch.
- the height of the object.
- how powerful the light source is.
Model how to write a specific question for investigation using the question stem beneath the variables grid, selecting one variable to change (controlled variable), one way to measure the outcome of changing that variable (in this case the height of the shadow), and noting that for a test to be fair everything else must stay the same.
If your students are experienced and confident in conducting fair-test investigations you might allow them to select their own variable to change and create their own investigable question. For example: What happens to the height of a shadow when we change the angle of the beam of light shone on it? Alternatively, the class can all agree on a single question to investigate, e.g. What happens to the height of a shadow when I change the distance between the light source and the object?
If allowing students to select their own variables to change, be aware that each team will then need to undertake the investigation in a slightly different way.
Discuss fair testing principles, including why it is essential to only change one variable and leave everything else the same: to ensure that we find out the impact changing a specific variable has on the outcome. If multiple variables are changed there is no way of knowing which one made the impact and to what degree.
In collaborative teams, students plan and conduct a fair-test investigation to answer their question, using a small object that creates a defined shadow. They measure the height of the shadow cast against a measurement screen or wall, change their specific variable (for example, moving the torch closer/further to the object at 5cm intervals) and measure the new shadow's height.
Discuss how the students will record shadow height, such as by using a measuring screen placed against a wall behind the glue stick, or measuring the shadow with a ruler or tape measure. Discuss the potential for inaccurate measurements.
| A demonstration of an investigation answering the question What happens to the height of a shadow when I change the distance between the light source and the object? | ||||
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Students should plan and record their investigation using the Shadow height investigation planner Resource sheet. They should not complete the Explaining results and Evaluating the investigation sections at this stage—this will be done at the end of the Integrate step of this lesson.
Discuss if the changes in the shadow are easy to read. Discuss how a graph is a different way to represent or show the same information as the table.
Consider if/what support your students might need to be able to graph their results using the provided graph template.
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
Adapting to your context—modifying this investigation
How might you modify this investigation for your students?
You might adapt/differentiate this investigation to suit your students and context by:
- changing the object.
- changing the intervals of measurement.
- modelling the arrangement of equipment.
- modelling how to record the results.
- collaborating on identifying their science question and planning the investigation.
- individually developing their own investigable question, identifying the variables and planning their investigation.
You might adapt/differentiate this investigation to suit your students and context by:
- changing the object.
- changing the intervals of measurement.
- modelling the arrangement of equipment.
- modelling how to record the results.
- collaborating on identifying their science question and planning the investigation.
- individually developing their own investigable question, identifying the variables and planning their investigation.
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
Using the QCER framework as a guide, invite each team to share the results.
Reiterate the question that each team has answered and the variables they have tested.
Invite teams to make a claim to answer the question, using their evidence from their data tables and graphs to support their claim. For the example students might answer the question What happens to the height of a shadow when I change the distance between the light source and the object?, by saying "the closer the light source is to the glue stick, the taller the shadow will be."
Consider how much support your students will need to complete the Reasoning section of QCER, and if required, complete this step together, using discussion and ray diagrams to support students.
A ray diagram can be drawn to show that, when the light source is closer to the object, the rays of light travel past its edges at a much steeper angle, causing the shadow to be taller.
The further away from the object the light source is, the lesser the angle and shorter the shadow.
Support students to generalise what they have learned about changing shadow height into other ways they might change the shape of a shadow.
- If shadows are taller when the light source is closer, how would we describe them when the light source is further away?
- The shadows are shorter/short.
- When did the shadow have the most clear and defined edge? When the torch was closer or further away?
- The shadow was much more defined when the light source was further away. When it was closer the edges of the shadow were more 'fuzzy' and less defined.
- When we moved the light source further away and the shadow got shorter, did it also make it wider? Did you notice that in your investigation?
- Model this again if students did not make observations of this during their investigation.
- When the torch was closer/shadow was taller it was also a little bit wider than when the torch was further away and the shadow was more defined. The difference wasn't really big though?
- Where might you position the light source to make a really wide shadow? Why do you think that?
- There are several suggestions that students might make in response to this. Consider testing out their suggestions as a demonstration, using what is learned from each test to inform where you might position the light source next.
- The shape and size of the object used to demonstrate will also impact what happens, so consider using different sized/shaped objects during the demonstration.
Students complete the explaining and evaluating results section of their Shadow height investigation planner Resource sheet.
Reflect on the lesson
You might:
- add new words and images to the word wall or glossary.
- add to the W and H sections of the TWLH chart.
- ask students to articulate exactly how they can make a shadow taller or shorter. Discuss how this might apply to making a shadow thinner, wider or a different shape.
- discuss how the learning from this lesson will be relevant to building their light sculptures at the end of the sequence: manipulating shadows to create desired shapes and sizes.