– Recognise that there is variation between animals including animals of the same type (species).
– Recognise that living things produce offspring of the same kind, but normally offspring vary and are not identical to their parents.
– Organisms within a species are similar but not identical, just as offspring are similar but not identical to their parents.
– The similarity occurs because most characteristics are genetically inherited from parents.
– Some characteristics can be new, and arrive through mutations (which are always occurring by chance). Mutations can be positive, negative or neutral. In other words, can improve, reduce or have no effect on an organism’s fitness (survival and reproduction).
– Variation is maintained in the population if the different forms have equal value to the survival and reproduction of an organism.
Starter (15 minutes)
Aim: To highlight the vast number of different animals found around the world. To introduce the term variation and characteristic. To emphasise there is variation in characteristics amongst different types of animals.
Important note: either of the main lesson options can follow either of the starter options.
Split the class into groups of between 4-6 children. Give each group a felt tip pen and a piece of white A3 paper. Ask each group to write down as many animals as they can think of in 2 minutes. Once the two minutes is up, ask each group to share a selection of their animals. As they name them, you should write them up onto the board. Continue around the groups until you have created a list of all the animals the class has thought of. Emphasise how many different animals there are around the world and congratulate the class on thinking of so many. Explain however that there are many more they have not thought of! For example, there are at least 900 thousand different types of insect in the world! And we are still counting….
Now ask the class if all the animals listed on the board are identical? The children should tell you that all the animals are different. At this point introduce the term variation. Explain how as the class have explained there is variation between all animals i.e. animals are different. However although animals are different, they also share common characteristics that make them similar. At this point define the term characteristic. Ask the class to think of some characteristics and create a list on the board i.e. the presence of fur, beaks, spikes, backbone, number of limbs etc. Now as a class chose two animals (for example a human and a cat) and discuss which characteristics are the same and which are different i.e. they both have four limbs but cats have fur whilst humans don’t.
Hand out the classification-worksheet (the animals on the first page of the worksheet should be cut up before they are given to the children). Explain to the children that they must split the animals and plants between the different circles on the worksheet. Explain that the circles represents the presence or absence of a characteristic for example the presence of fur. They must start on the “fur” vs “no fur” side. Once finished (and checked with you) they should move on to the other “photosynthesis” side. Once they have completed both sides of the worksheet bring the class together and discuss the children’s answers. The discussion should highlight that although animals are different, they also share common characteristics that make them similar. Explain how the name for these differences is variation. At this point emphasise how many different animals there are around the world and thus how much variation can be seen. You could perhaps get the class to create a list on the board of all the animals they can think of around the world. Then explain that there are many more they have not thought of! For example, there are at least 900 thousand different types of insect in the world! And we are still counting….
Main Body (30 minutes)
Aim: To highlight how there is variation between animals of the same type i.e. between cats. To highlight how there is variation between parents and offspring.
Next, focus in on one type of animal – for example a cat. Ask the children whether every cat is the same. They should tell you that there are lots of different cats. Emphasize that this means there is variation even among the same type of animal i.e. cats. A PowerPoint slide with 20 pictures of different cats all next to each other would be a great visual aid to show the large amount of variation even within one type of animal. Talk about differences in characteristics such as size, shape, fur colour, fur texture etc.
Give each child a copy of the cat-worksheet (this would be better if printed in colour) and instruct them to match up the parent cat to its offspring. Once everyone has completed the worksheet ask the children whether the offspring are identical to their parents. They should find that although they are similar they are not identical to their parents. Emphasise how this shows that variation exists even within a family. Discuss with the class why offspring are not identical to their parents or each other. Explain that mutations can occur when offspring are produced which cause changes in certain characteristics for example on the Persian cat the parent is all white whereas mutations (define mutation) may have caused the offspring to have patches of brown or black fur. Explain how variation in offspring can be positive (increase their survival), negative (decrease their survival) or meaningless (have no effect on survival).
What kind of mutation would a change in colour be for a domestic cat? (neutral)
What if the change in colour was for a beetle to become bright yellow? (Likely negative, as it would be easier for birds to see it and eat it)
Thus, the values of new characteristics depend on the species and the environment.
Ensure an open space such as a playground, hall or field is available. Tell the class they are going to act as animals in the wild trying to get enough resources (food, shelter and space) to survive. There are therefore three challenges which the children must try and complete (challenges are explained here). The children should split into pairs and try to complete as many challenges as possible within the 10 minute time frame. Have 15 different stations spread out on the playground (you can have them ready in plastic tubs spread around the playground). The pairs must move around completing as many tasks as possible, they can repeat the same activity more than once. The winner of each task must collect a survival counter from the pot of counters, in the middle of the playground, after winning each task.
Once the 10 minutes is up ask each child to count up how many counters they have. Write down their scores on the board. Explain how even within their class (the same type of animal) there is a lot of variation between the numbers of survival counters each person has. This is because each pupil is different to the other pupils, they have strengths and weaknesses which make one human better at some tasks than others for example some are taller, some have better eye sight, some have small hands or big hands etc.
Now ask the children what they think would happen if they played this game with their parents and siblings. Would the siblings and parents get the same results as them or different? Explain how you would expect them to get different results as although we are similar to our family we are also different, i.e. there is variation between parents and offspring and between offspring. Try to ensure the discussion is kept around characteristics, for example “I can do this task better than my brother because I have better eyesight”.
***This activity may not be appropriate if there are adopted children in the class***
Plenary (10 minutes)
Complete the lesson assessment as the plenary to check student understanding:
1) Are all animals identical?
2) Are offspring similar to their parents?
3) Are offspring identical to their parents?
4) What is the term given to the differences seen?
5) Can new characteristics not seen in parents appear in offspring?
Answers: 1) No 2) Yes 3) No 4) Variation 5) Sometimes, but this is a rare event called mutation
This is a great game which explores mutations and variation, and could provide a good extension: http://www.usc.edu/org/cosee-west/AprilLectureMaterials/Activities/Mutations&Variation.pdf