Unit 7: Sorting and classifying plants and animals

Transcription

1 Elementary Science Unit 7: Sorting and classifying plants and animals Teacher Education through School-based Support in India

2 The TESS-India project (Teacher Education through School-based Support) aims to improve the classroom practices of elementary and secondary teachers in India through studentcentred and activity-based approaches. This has been realised through 105 teacher development units (TDUs) available online and downloaded in printed form. Teachers are encouraged to read the whole TDU and try out the activities in their classroom in order to maximise their learning and enhance their practice. The TDUs are written in a supportive manner, with a narrative that helps to establish the context and principles that underpin the activities. The activities are written for the teacher rather than the student, acting as a companion to textbooks. TESS-India TDUs were co-written by Indian authors and UK subject leads to address Indian curriculum and pedagogic targets and contexts. Originally written in English, the TDUs have then been localised to ensure that they have relevance and resonance in each participating Indian state s context. TESS-India is led by The Open University and funded by UKAID from the Department for International Development. Version 1.0 Except for third party materials and otherwise stated, this content is made available under a Creative Commons Attribution-ShareAlike licence:

3 Contents Introduction 1 Learning outcomes 2 1 Overcoming misconceptions in identifying living and non-living things 3 2 Sorting living and non-living things 5 3 Introducing classification keys 9 4 Using classification keys 10 5 Introducing variation within a species 13 6 Summary 15 7 Resources 16 Resource 1: Kingdoms of living things 16 Resource 2: Vertebrates and invertebrates 16 Resource 3: Tabular keys 17 Resource 4: Carroll diagrams 18 8 Related units 20 References 21 Acknowledgements 22

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5 Introduction Introduction Elementary-level students are often asked to sort and classify a collection of objects. All scientific work requires the fundamental skills to:. recognise the similarities and differences between a set of objects. sort and classify them according to particular criteria. identify patterns and common features among them. Sorting and classifying has applications in most areas of the elementary science curriculum. These include plants, food groups, rocks and soils, chemical elements and manufactured materials, for example. This unit will focus on living and non-living things. However, the suggested grouping and classification activities should be transferable to other areas of scientific study. An early distinction students need to develop is that between things that are alive and not alive, in order to begin to appreciate the different elements of their immediate environment. The ability to recognise and name similar animals or plants is a first step in accurately identifying a species and learning about it in more depth. This unit will explore ways you can support your students in sorting and classifying living and non-living things using techniques such as Venn diagrams and classification keys. 1

6 TDU 7 Sorting and classifying plants and animals Learning outcomes After studying this unit, you should be able to:. identify ways of supporting your students understanding of the distinction between living and non-living things. integrate practical sorting activities into your elementary science lessons, based on Venn diagrams and classification keys. 2

7 1 Overcoming misconceptions in identifying living and non-living things 1 Overcoming misconceptions in identifying living and non-living things Pause for thought Thinking back to your previous teaching experience:. What difficulties do you think younger students might have in distinguishing living and non-living things?. Do you think older students would be able to define the difference between the two?. In what ways could you help students to understand the difference between something that is living and something that is not? Students of all ages will have certain misconceptions when identifying something that is living and something that is not. Confusion can occur as many things may not appear to be living. Plants are one such example. Younger students may not understand that plants breathe, reproduce, move and change, as these processes are not immediately visible. Older students may classify something as living by using a simple checklist with questions such as: does it breathe, move, excrete, feel, grow, consume and reproduce? Although this kind of checklist is useful, it s important to recognise that not all living things will do all of these activities. Worker bees do not reproduce, for example, while other living things, such as seeds and bulbs, remain dormant for long periods. There are various ways that you can support your students in identifying living and non-living things. You can demonstrate to younger students that a plant is alive and moves, grows and reproduces by showing them pictures and photographs of its lifecycle and explaining how it changes over time. Giving younger students the opportunity to plant seeds and make observations over time will help them understand that small changes do take place over given periods. This will establish that seeds and bulbs are alive, but that it is necessary to give them the conditions they need for growth. Carrying out a simple visualisation activity can help your students determine if something is living or not. Try it for yourself, and think about how this may help your students. Figure 1 shows an example. 3

8 TDU 7 Sorting and classifying plants and animals Figure 1 A visualisation activity for students. A variation on this activity would be to ask your students to draw what they imagine the tree and the car look would like in 50 years time. You may have to explain that, left to themselves, most non-living things will break down and become simplified over time as their materials disperse into the environment. In contrast, many living things will spontaneously become larger, more complex and more numerous. A checklist of the so-called seven life processes (Table 1) can be used to support older students in identifying if something is living. Table 1 A checklist of the seven life processes. Does it Yes/No breathe? move? excrete? feel? grow? consume? reproduce? Students need to develop a good understanding of each of these processes and be made aware of common exceptions such as the worker bees, mentioned above, and crystals, which grow but are not alive. Older students can write their own version of a checklist to identify if something is alive or not. This would be a real indication of their understanding of life processes. TDU 3, Using explanations as a teaching strategy: life processes, explores life processes in more detail. 4

9 2 Sorting living and non-living things 2 Sorting living and non-living things Pause for thought. What have been your experiences of teaching living and non-living things to your students?. Have you used simple sorting activities in any area of science before? What did this involve? A good starting point when introducing the concept of living and non-living things is to provide your students with a collection of items to sort into a simple Venn diagram, with simple headings as in Figure 2. Refer to TDU 12, Collecting, recording and displaying data: heat and temperature, for more examples of Venn diagrams. Figure 2 A Venn diagram. You could collect the items for sorting yourself. However, asking your students to bring items to add to the collection will make the activity more meaningful to them. The collection might include such things as:. a piece of wood. some leaves. aplant. some seeds. a spoon. some fruit. a stone. asnail. a glass bottle 5

10 TDU 7 Sorting and classifying plants and animals. a piece of tree bark. As the teacher, you could perhaps include a small living organism (sometimes referred to as a mini-beast) in one of your sorting activities, but this must be returned to its natural habitat as soon as possible. Do not encourage your students to contribute any living things to the collection themselves. The collection of items should stimulate discussion among your students as to what is living and what is not. Including a piece of fruit, or a fossil, in your collection will provide opportunities to discuss the idea that something could be classified as once living or in the process of decaying, but with the potential to grow again. Providing your students with a magnifying glass will enable them to examine an item more carefully. Older students can write down the items they feel should go under each heading, whereas younger students can complete the task in a more practical way such as physically placing the items into hoops or circles on a table. Open-ended questioning should be used to stimulate discussion. For example:. Where do you think this came from?. Why do you think it is living or non-living?. What would happen to this if we left it outside on the soil? For more ideas on open-ended questioning, see TDU 5, Using questions to extend students understanding of forces. An initial sorting activity like this will help you to establish what your students know about living and non-living things and should inform your planning of subsequent teaching activities. Successive lessons could include agreeing a definition of living and non-living things and constructing a checklist to support future identification work. You could arrange or organise a walk around the school grounds to identify living and non-living things together. Continuous and comprehensive evaluation (CCE) As discussed earlier, students of all ages will have misconceptions when identifying living and non-living things. Your students understanding of living and non-living things can be assessed by asking them to complete simple sorting tasks and providing opportunities for them to explain why they sorted things the way they did. The following activity asks you to identify what two students understand by the terms living and non-living. 6

11 2 Sorting living and non-living things Activity 1: Identifying students misconceptions about living and non-living things Look at the two work samples in Figures 3 and 4, from a student in Class I and Class V respectively, and list the misconceptions that each of them appears to have about living and non-living things. Then note down what you could do to support their understanding in future lessons. Figure 3 Sample 1, from Class I students. Figure 4 Sample 2, from Class V students. Discussion Read the notes in Table 2 and compare them to your own ideas. You may have thought of other ways of supporting the students in distinguishing living and non-living things. 7

12 TDU 7 Sorting and classifying plants and animals Table 2 Students misconceptions, and ways of providing support. Sample 1: Class I student Misconceptions in the drawing:. The student thinks the car is a living thing.. The student does not recognise a seed as living. Ways of supporting the student:. Find out why they think the car is living.. Create a simple checklist for living and non-living things with the student, then revisit the original activity.. Plant a seed with the student and observe it over time, noting down the changes and comparing them against the checklist made earlier. Sample 2: Class V student Misconceptions in filling in the checklist:. The student does not think a tree reacts to its surroundings.. The student does not understand that trees create waste products.. The student does not understand that a fossil was once living. Ways of supporting the student:. Show photographic examples of trees reacting to their environment such as their leaves reacting to a lack of water or to too much sun.. Review the process of photosynthesis, using a flowchart.. Explain that a fossil was oncealivingcreature,using simple diagrams.. Support the student with sequencing the process of fossilisation from beginning to end. 8

13 3 Introducing classification keys 3 Introducing classification keys Pause for thought. Have you used a classification key (also known as a dichotomous key) with your students? How did this help your students with classifying things?. Have your students devisedtheirownclassification key?. What other methods of classificationhaveyouusedwithyour students? As students investigate the differences between living and non-living things, they will become increasingly aware of the variety of life forms. At this stage, their learning should progress into more detailed observations and forms of classification. Students should begin to explore the different ways that living things can be identified. Resource 1 discusses the various ways that living things can be classified. Younger students can begin by sorting living things into animals and plants. The animals can then be further sorted into those that have legs or no legs, or those that fly, swim, walk or crawl. These early sorting activities should be done practically using pictures, photos or plastic models, where available. As students become more confident with sorting living things and using set criteria, they can be introduced to simple classification keys. A classification key sorts living things by identifiable features. Students will start at the top of the key, with one large group of items, and then, by answering a series of questions, will subdivide the group into smaller and smaller sets. Figure 5 shows an example of a basic classification key. 9

14 TDU 7 Sorting and classifying plants and animals Figure 5 Classification key for mini-beasts. The following case study describes how a teacher introduced classification keys to her class and supported her students in developing their own. 10

15 4 Using classification keys 4 Using classification keys This section presents the experiences and reflections of a teacher as she introduced classification keys for living things to her students, and guided them in making their own classification keys. Case Study 1: Mrs Suringha introduces classification keys to Class III Mrs Suringha, a teacher of Class III, had carried out various sorting activities with her class. She knew that her students had a good knowledge of the differences between living and non-living things. She identified a group of able students in her class who were ready to use and create classification keys, and another group of less-able students, who would need her support. Here she describes how she introduced classification keys to the two groups. After undertaking lots of sorting activities with my students, I decided to introduce them to classification keys. I began the lesson by showing them pictures of a crab, a cat, a tree, a bird, a butterfly andaflower. I asked my students to work with a partner and decide how the living things could be grouped together. After five minutes we discussed the various ways we could organise the pictures. As each student made a suggestion, I moved the pictures around. For example, when the class suggested creating an animal and plant group, I moved the pictures so that the animals and plants were placed together. I continued to do this until each picture had been placed in a sub-group. I showed the class an example of a basic classification key and explained that the initial group of animals was sorted and subdivided following a series of questions. After identifying two animals using the example classification key, I linked the pictures, which we had sorted earlier, with arrows. I wrote Yes and No by each one, and explained that, as a class, we were going to write the questions that would subdivide each living thing we considered. I wrote the firstquestionatthetopofthepictures: Is it a plant? and asked my students to work in small groups to devise the other questions. After five minutes we discussed the various questions we could write on the classification key and agreed the best ones to use. Finally, I wrote the students questions above each branch to complete the classification key. Below [Figure 6] you will see the classification key made by my class. 11

16 TDU 7 Sorting and classifying plants and animals Figure 6 Classification key created by Mrs Suringha and her Class III students. I then divided the class into two ability groups and explained the next task to my students. I gave each student a blank classification key and asked them to devise the questions that would subdivide each living thing we considered. I asked the group of more-able students to work independently while I worked with the other students, as I felt they would need more support. Below [in Figure 7] you will see the blank classification key that I used with my students. Figure 7 Blank classification key used by Mrs Suringha and her students. Working with my less-able students I began the task by showing them six possible questions which could be used to identify each living thing at the bottom of the classification key. Here are the questions that I used:. Does it have four legs? 12

17 4 Using classification keys. Does it have legs?. Does it have a shell?. Does it crawl?. Does it grow from a tadpole?. Does it have a short tail? I began by asking my students to suggest how the questions on the classification key could be organised so that they were appropriately sequenced. After some discussion, one student suggested working backwards and by organising the questions from the bottom of the key. When both groups had finished the task I gave my students the opportunity to share their questions. Finally, I asked my students to swap their classification keys with a partner and gave each student the name of an animal on the key. I asked the students to check that the classification key worked by using it to identify the animal. Reflection The classification keys produced by the group I worked with were more effective and had fewer mistakes than those of the group that worked independently. If I were to teach this lesson again, I would give the same six questions to all students. I would also provide them with more opportunities to use classification keys before asking them to attempt their own. Pause for thought Think about the class that you currently work with, and answer the following questions:. Are your students ready to use classification keys?. How do you think you would introduce them to classification keys?. How would a similar activity to that of the case study above help your class understand classification keys? 13

18 TDU 7 Sorting and classifying plants and animals 5 Introducing variation within a species As students progress, they can begin to explore variation within the same species (a group of the same living organisms). The following activity asks you to undertake a simple classification task with your students. Activity 2: Exploring human variation among members of your class A good way of introducing your students to the concept of variation within a species is by asking them to compare themselves with their classmates. This activity is suitable for students of all ages, as they will develop grouping criteria according to their level of ability. It is important that your students are given the flexibility to sort themselves into groups, based on the features that they decide they have in common (or not). You will no doubt be surprised at the many ways your students will organise themselves! It is important to help your students to be sensitive to the differences between one another by suggesting that some of the differences that could be pointed out might cause offence or upset, and should be avoided. Exploring classroom variation At the start of the lesson, explain that everybody in the class belongs to the same group of living things called humans and that, although they all belong to the same group, they are all different. 1 Divide your students into groups and ask them to organise themselves by features they have in common and those they don t. For example, students could organise themselves according to gender, height, hair length, etc. 2 As your students are working, encourage them to observe the similarities and differences that there are between one another. 3 If you are working with older students, you could supply them with measuring equipment so that they could compare hand spans, foot lengths and arm lengths, for example. 4 Ask your students to note all the ways that they organised and grouped themselves, and the similarities and differences that they observed. 5 At the end of the lesson, list all the similarities and differences that the students identified, and draw attention to the amount of variation within the class. Extending the activity Thisactivitycanbeextendedbyaskingstudentstorecorddataand present it in a graph. You could choose just one criterion, such as hand 14

19 5 Introducing variation within a species span, and help your students collect and represent the data that they collect. A follow-up activity could involve investigating whether the students with the biggest hands have the biggest feet. This activity also provides an opportunity for you to introduce older students to the terms continuous variation and discontinuous variation. Continuous variation is a species characteristic that has a range of values, such as height, that can usually be plotted on a graph. Discontinuous variation in contrast is a species characteristic that has only a limited number of possible values, such as gender and eye colour, and is usually plotted on a bar chart. A useful reference for this is a Variation and classification document (BBC, undated). Pause for thought Reflect on the activity in this section, and in particular:. What went well during the activity and what would you change next time you undertake it?. Do you feel your students had a better understanding of variation by the end of the activity?. In what ways did you support them?. In the light of this lesson, what are you planning to teach your students next?. Did you complete the extension activity to include analysis of data? 15

20 TDU 7 Sorting and classifying plants and animals 6Summary Students need experience of sorting and classifying living and non-living things into related groups. This has implications across the whole elementary science curriculum, as the skill of classifying can be applied to most areas of scientific study. Students may have misconceptions about living and non-living things. Until they understand what it means to be alive, they may struggle with more complex classification activities. Identifying any student misconceptions and planning activities that change their thinking will support their future understanding of living systems. Students can be helped to classify living things by using classification keys. Having had experience of using classification keys, students should then be encouraged to create their own versions. As students investigate the differences between living and non-living things they will become more aware of the variation among life forms. By exploring the differences and similarities between themselves as humans, they can begin to develop an understanding of variation among the same species. 16

21 7 Resources 7 Resources This unit has focused on simple ways of sorting living organisms. Once students have developed a good understanding of living and non-living things, they can be introduced to more complex ways of classifying them. The following resources include images that can be used with your students to explain other ways that living things can be organised. Resource 1: Kingdoms of living things Initially living things can be organised into one of the five kingdoms. Figure R1.1 shows the names of the kingdoms and examples of living organisms you would find in them. Figure R1.1 Examples of living organisms. Resource 2: Vertebrates and invertebrates Plants can be divided into two groups: flowering and non-flowering plants. Non-flowering plants have no flowers. Examples include algae (seaweed), fungi (mushrooms, mould), conifers and ferns. Flowering plants are those that produce flowers during their lifecycle. These include rose bushes, apple and cherry trees, grasses and cereals. Animals can be sorted into animals with or without a backbone. Animals that have a backbone are known as vertebrates. They have a skeleton inside their body and can be subdivided into fish, amphibians, reptiles, birds and mammals. Animals that don t have a backbone are called invertebrates. They have soft bodies and can be subdivided into cnidarians, worms, arthropods and molluscs. Arthropods have a hard outer coating with segmented bodies and jointed legs. As this is such a large group, it can be subdivided again. Arthropods can be divided into millipedes, centipedes, arachnids, crustaceans and insects. 17

22 TDU 7 Sorting and classifying plants and animals Students can continue to produce increasingly more complex classifications as their knowledge of living things develops. For example, they can sort animals into omnivores, herbivores and carnivores. They can create their own classification cards for amphibians, reptiles, mammals, birds and fish, explaining the differences between these animals. An example of how to sort animals is shown in Figure R2.1. Figure R2.1 An example of how to sort animals. Resource 3: Tabular keys Tabular keys, like classification keys, can be used to sort and classify living things. Students should start at the top and work through the questions until the living organism has been identified (Figure R3.1). 18

23 7 Resources Figure R3.1 Using a tabular key. Resource 4: Carroll diagrams Carroll diagrams such as Figure R4.1 can be used to sort objects, numbers and living things by a set of given criteria. In this case, the living organism should meet the criteria in a given row and column before being placed into a box. Figure R4.1 Using a Carroll diagram to sort animals. 19

24 TDU 7 Sorting and classifying plants and animals 8 Related units The following units are particularly closely linked with the content of this unit.. TDU 2, Using group work to explore floating and sinking: This unit explores objects that float and sink. Students use a Venn diagram to sort materials that float and sink.. TDU 12, Collecting, recording and displaying data: heat and temperature: This unit explores the different ways in which students can sort, record and display data. 20

25 References References BBC (undated) Variation and classification (online), KS3 Bitesize (Science revision aid). Available from: organisms_behaviour_health/variation_classification/revision/3/ (accessed 14 January 2014). Hollins, M. and Whitby, V. (2001) Progression in Primary Science: A Guide to the Nature and Practice of Science in Key Stages 1 and 2 (2nd edition), Roehampton Studies in Education. London: David Filton Publishers. Wenham,M.W.(2004)Understanding Primary Science: Ideas, Concepts and Explanations (2nd edition). London: Paul Chapman Publishing. 21

26 TDU 7 Sorting and classifying plants and animals Acknowledgements The content of this teacher development unit was developed collaboratively and incrementally by the following educators and academics from India and The Open University (UK) who discussed various drafts, including the feedback from Indian and UK critical readers: Jane Devereux and Christine James. Except for third party materials and otherwise stated, this content is made available under a Creative Commons Attribution-ShareAlike licence: The material acknowledged below is Proprietary and used under licence (not subject to Creative Commons Licence). Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: CCE logo: Drawings using clip art: by permission from Microsoft. Activity 1: samples from unidentified students. Every effort has been made to contact copyright owners. If any have been inadvertently overlooked, the publishers will be pleased to make the necessary arrangements at the first opportunity. 22

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