Lesson on Molluscs

For Class 5: Animals that build shells- Lesson 1.
Methodology : Hands on experience with shells
Time needed : 1hr. 30 minutes ( can be planned for 2 classes for 40 minutes duration each)

Aim : Establish a bond with the natural world especially with ocean dwelling animals. Develop higher order thinking skills from a very young age.

Specific objectives : ( Learning outcomes that can be tested for knowledge)

  1. To become familiar with the texture and shape of shells
  2. To know the names and at least three features of commonly seen shells such as cowries, cones, moons, clams, whelks, mussels, top-shells, frog-shells etc.
  3. (Study and understand the features necessary, to) Acquire knowledge of how molluscs adapt to their environment and of the role of humans in their habitat.
  4. Develop the ability to communicate in formal scientific language ( develop specific vocabulary and its usage)
  5. To develop observation, drawing and writing skills
  6. To kindle and keep alive curiosity for the natural world

Teacher preparation :

This is what you need to keep ready for the class :

  1. Different kinds of shells. You will need at least 3 shells per group of 4-5 students.
  2. If you do not have shells then use the presentation on shells given in this website. This means you will need an LCD projector. If you do not have an LCD projector then copy the images on a transparency and use an overhead projector.
  3. Notebook, pencils, colouring materials(colour pencils, crayons (oil pastels), water colour or charcoal.
  4. If you are doing this during monsoon time, then you may collect the little slugs that come out during this season; you may also use garden snails but please remember that these are not molluscs that live in the ocean. They should be used for review to develop higher order thinking skills(HOTS).

Action in class :

  1. Divide your class into small groups.( ideal number is 4/5 to a group)
  2. Give at least 2 shells to each group.
  3. Ask students to observe the shells;Feels its surface, smell it ( but not taste it). Give them 4/5 minutes to observe and talk amongst themselves about the shell.
  4. By now the class noise would have reached a certain crescendo due to excitement. Calm them down so that the activity of observation and discussion is not lost in idle chitchat.
  5. At the end of 5 minutes ask everyone to draw the shells given to them. This should take them close to 10 minutes.
  6. At the end of 10/12 minutes ( keep some extra time for slow students) use the projector to show the parts of a shell. Your projections must show the parts of a univalve(gastropod) and bivalve shell. Ask the students to observe the parts marked on the shell and look for those parts in the shells given to them. The parts you are concentrating for this level would be : Dorsal, ventral and foot for both univalve and bialve shell; apex in the univalve shell and beak for the bivalve. The anterior- posterior concept in these shells can confuse students of this age group and hence to be dealt with only if the teacher is confident of leading a good discussion
  7. Ask one student from each group to stand up and point out in her/his shell the parts mentioned. Ask them to give reasons for their answers. Ask :Why are these shells necessary ? How do the animals move?
  8. In order to clarify the concept of dorsal and ventral ask the students to point out that part of their body which is dorsal and that part which is ventral. Follow it up by asking how one would know which is dorsal and which is ventral in any animal.
  9. If you have time ask students to imitate a frog jumping, an elephant walking, snail crawling, a snake slithering and then question to find out whether they can say which is dorsal and ventral in each of these cases. Follow it up through questioning and discussion that the part that faces the earth ( is towards earth, generally during movement)is ventral and the part that is away from the earth is dorsal.Ask questions related to the muscular foot used for movement. Through questions find out what the students know about the term ‘muscular’ and ‘foot’. It always helps to draw comparison with their own body to understand differences.After they have given their answers, summarise the lesson and the facts learnt so far, in order to clarify the doubts that may be there in the minds of a few students.Summary by you at the end of the class will have the following points :The shells are the houses in which certain soft-bodied animals live. The shell protects them. Each animals builds its own shell.These animals can be seen on land, freshwater and oceans, but the shells that we are studying today are those of animals seen in the oceans.Some of these animals build shells that have two parts and are called Bivlaves and those(animals) that build with one only are called univalve. The word ‘ valve’ is used to describe the 2 portions of a bivalve shell.The tip of the univalve shell is called apex where as the pointed end of the bivalve is called beak.All animals have a dorsal and ventral portion. Similarly the shells also have a dorsal and ventral part. The term dorsal refers to that part of the body that is away from the earth where as the ventral part is the one that is towards the earth. In human body we use the term ‘back’ for dorsal and ‘front’ for ventral.Introduce the word ‘secretion’ as a process by which the animal makes its shell. Explain the word secretion as a process by which any animals makes substances needed for its use. Give saliva as an example of human beings make it.

    Explain about shells : Depending on how an animal makes its shell, some may be smooth where as others may be rough; some would have no designs other would have patterns. They also have different colours. The colours are also because of the way the animal secretes substances for making its shell.

    These soft bodied animals have a foot that is ‘muscular’, meaning made up of muscles,no bones; how the foot comes out and how it is used in locomotion. ( Ref to Phylum mollusca for locomotion)

  10. Now ask all students to mark the parts in their diagram
  11. If your class is for 40 minutes then you stop here and give them some work to do at home. This is a way of assessing how much they have understood.*1

Assessment :

Colour the drawing done in class and answer (select one or two from the questionnaire) the questions

Print out the pencil images of molluscs given and ask them to choose any one.Draw and mark the parts.
Give the questionnaire to assess what and how much they have learnt.
Pencil images for drawing, colouring and marking parts or taking with you if you are going to conduct this as an outdoor class on a beach.

Questionnaire for assessment ( available in PDF)

I.The sentences given below are incomplete. For each incomplete sentence there are three answers given. One of them is the correct one. Choose the correct answer and complete the sentences. Remember to rewrite the complete sentence.

1. Molluscs need shells to ———-
a) protect their soft body
b) because they do not have bones
c) to move in water.
2. In a bivalve shell the beak can be seen on ————–
a) the front of the shell
b) left side of the shell
c) dorsal side of the shell

3. In a cockroach the wings are present on the ———-
a) dorsal side
b) ventral side
c) near its neck.

II. 1. Why do animals make shells?
2. What do you mean by the term Univalve?
3. what helps animals make colourful shells?

*1 If your class is for 1hour 30 minutes then pause at this moment and ask students to write 3 sentences about the shell they have in their hands. Give them specific instructions that they must use the vocabulary learnt while answering the question. This will take about 15 minutes.

Continue discussion on the shape and texture of the shell. Discussions will help elicit answers only if the questioning technique is right. The following questions are given as examples. ( You may design your own too )

1. Ask questions related to texture of shells
2. What would the shell be made up of?
3. Some shells are used to make lime that is used to whitewash houses. So what do students think the shells are made up of?
4. Where do animals get the materials to build the shells
5. How do they manage these shapes?
6. Take two bivlve shells and show how it opens and shuts. Now ask what is needed to open and shut the shells (hinge).Ask them to observe the hinge area and write about it.
7. Project different kinds of shells and ask them to describe the shape of the shells in one or at most two words. Then you show them the names that are generally used to describe these shells and ask them to respond.( screw shells, Cones,wedge,cowry,conch etc depending upon the shells you are able to get for the class)

Take 25 minutes for the discussions then give them the three multiple choice questions to answer in the next 10 minutes.Reduce homework to merely colouring the shells they have drawn in class.
Animals that build shells- Lesson 2

Ideally this lesson should be preceded by some writing exercises for 40 minutes in class. The writing exercise should consist of questions that will encourage descriptive form of writing where the following aspects of writing can be developed :-

use of scientific vocabulary; writing in a formal way to communicate facts, reasons, analysis and conclusions; ability to express inferences clearly, logically; ability to communicate clearly through descriptive explanations;

Methodology : Outdoor class- Field work

Having got the students to look at the shells it would be ideal to take them on a field trip to see the habitat of the shells.
This lesson is for all those who live by the sea-side or in places where there is an ocean/sea
Time needed : At least 2 hours.(1hr for travel and 1 hour of class time.)

Objective of the lesson :

To familiarize students about the environment in which animals (mollusks) live.—Habitat study
To improve observation and thinking skills.

Planning for the outing :

General Planning :

1. Important for the teacher to familiarize herself/himself with the field-area before taking the students.
2. Adequate safety measure to be planned. This should include demarcation of boundaries (the places the students can go up to and places that are out of bounds at the sea-side.)
3. Making suitable adjustments with other teachers and school so that adequate time is available.
4. Taking care of formalities such as permissions from school, parents/guardians etc.
5. Co-opting other adults for the field trip( parental help could be taken if co-teachers cannot be spared)Ideal plan is to have one adult for every 5/10 students.
6. Clear instructions to parents and students about the objectives of the field visit, safety measures adopted and things to be carried especially a water bottle and a cap.

Lesson related planning :

1. Keep an observation sheet ready to distribute to students.
2. Ensure that all students are carrying a notebook, pencil, rubber and pen.
3. Ensure that students are divided into groups and are informed in advance. Each group also knows the teacher who will be in-charge of them.
4. Share your class plan with other adults accompanying you so that time is well utilized.
5. Plan your class thus :
* Gather students for instruction and distribution of the observation sheet. Highlight that observations on the beach must also include activities related to mollusks. (Expalin the dos and don’ts)
* Walk along the instructed area for 10/15 minutes and then choose a place to sit down and observe (if any) activities on the sand. This can go on for another 15 minutes when students observe and fill in the observation sheet.
* Ensure that the area for observation is clear of dangers such as water currents, rocks etc. Choose safe areas.
* If it’s a calm sea/a lagoon then permit students to stand near the water or into the water and observe. Safety of students is the highest priority.
* Quite likely that crabs and not shell might catch the students’ attention. Do not worry about it.
* At the end of 30-35 minutes gather all students to a designated place and begin discussions.
* Discussions and sharing can go on for about 30 minutes after which you give them some questions for homework before starting your return journey.



Sea-side related


1. What you felt

2.What you saw

3. What attracted your attention the most.

Use words to describe how you felt, what was causing that feeling;

2. How was the beach? How was the sea? (about the soil, sand,water, any other things seen)


Living organisms (plants and animals)


1. Where did you see them?

2. What were they doing?

3. Colour, size, shape and any other feature that attracted you.

Did you see any shells?

Did they have animals inside or were they empty?

Note down all those things that interested you about the creatures you saw.
3. Non-living things seen

NOTE : If you are unable to find the right word to describe what you are seeing then take help from your teacher. If you wish to draw what you are seeing then do it wither in your notebook or on the back side of this sheet.

Questions for discussions :

1. Permit random observations from students about what they saw, heard, felt, smelt and tasted?
2. Question them about the habitat? Would they call it soil or sand on the beach? (At a later discussion you can ask for differences between the two)
3. Was the sea water washing away the shells or were they to be seen? Why? How? Etc etc
4. Where did the creatures they observed get their food from? Questions on – Did they think whether these creatures were breathing, eating, etc etc
5. What kind of dangers these creatures faced ? How could they escape from these dangers.
6. Ask a few questions about the non-living things seen on the beach. Try and connect it to the need for keeping beaches clean.

Homework questions :

1. Describe the beach they visited (in four or five sentences.)
2. How many different living creatures did they see?
3. Write two important features about the animals they observed?
4. How do these animals protect themselves when in danger?
5. Did they see any plants? If they did not, then explain the reason for their absence.
6. Draw at least one of the animals observed by them.

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