Lesson 1 What varies?
1 Introduce the Thinking Science course to the whole class. Explain it is a little different to their other science lessons. These ‘brain training’ lessons happen about once a fortnight. The focus will be on the way pupils think about the problems, not just on getting the answers right. It is helpful if you set down the ‘rules’ for a Thinking Science lesson where these differ from your normal school practice: e.g. homework, marking of class work, keeping Thinking Science Notesheets separate from other science notes, working in groups (see ‘Notesheets’ on page 4 for our suggestions). (5 minutes)
Start Lesson 1 by asking ‘what do scientists do?’ You may elicit ideas such as ‘do experiments’, ‘investigate’, ‘measure things carefully’. Lead discussion to a point where you can say that one of the things we are interested in in science is relations, or connections, between different things. For example:
‘If there are a lot of berries on the holly, it will be a cold winter.’ ‘Black cars have more accidents than yellow cars.’
We can study how true these statements are by seeing whether there is a relationship between the number of berries and the coldness of winter. (You could discuss ‘relations’ briefly in terms of family relations – some sort of connection.) But first we must be clear what it is we are looking for. What are the things that vary, or differ? We use the word variable to describe things that can vary. In these examples:
|number of berries in winter; coldness
number of accidents; colour of car
2 Now for a practical ‘test’ to see how much they have understood so far. Spread a number of books about on a table where all can see. Ask pupils to give some ways in which these books differ from one another, how they vary.
For example: ‘size’ – yes, they vary in size, size is one variable. What other variables are there? And so on for colour, cover type, or whatever else comes up. Write up a list under the heading ‘variable’.
Now, what values does each of these variables have? The values of colour are red, blue, green, etc. For each variable in the list, get pupils to suggest values – which may just be ‘big’, ‘medium’, ‘small’ (try to avoid getting into definition problems at this stage). (5 minutes)
3 Activity 1: coloured shapes.
Put the books away, and lay out (or stick up) where all can see, the set 1 shapes: three blue triangles and three red squares.
Hand out one Notesheet per pair or group of pupils.
Pupils should be able to identify the variables (size, shape and colour) and values (small/ medium/large; square/triangle; red/blue). These go in the first table of the Notesheet.
Now is there any relationship between them? Do shape, colour and size ‘go together’ in any way?
Ask each group to spend 2 minutes discussing and answering these questions on their Notesheet. After 2 minutes (no more) elicit something like ‘triangles are all blue’. Colour and shape are related, there is a connection between them.
Spend a few minutes getting them to predict, for example: if you were to say the next shape you bring out would be blue, pupils can tell that the shape must be a triangle. If the next shape you show were to be a square, pupils can predict that it would be red. A relationship between variables allows you to say what will happen next. (10 minutes)
4 Use the set 2 shapes. Now lay out the large blue square, large blue triangle, medium red square, and medium red triangle. These are the same variables – but what is the relationship now? Elicit that colour is related to size. (Table (2) on the Notesheet.) (5 minutes)
5 Activity 2: coloured containers. Produce the four prepared containers. Briefly discuss the variables (that they can see): colour and size. The values: red/ blue; large/small. Relationship: colour goes with size.
Now feel the weight of two of the containers in your hand, and push forward the balance, as a clue to, ‘what other variables may there be?’ If necessary, get a pupil to feel the weights of the small lighter and big heavier container.
Get them to talk about how to fill in the Notesheet in groups of between three and five pupils. As necessary, help pupils to complete Table (3) on the Notesheet, except for the weight column.
Your weights may be different but this is the pattern. Physicists may be irritated by this non-rigorous use of grams as a measure of weight. Our view is that using either alternative of ‘mass’ or ‘Newton’ would require an explanation that would confuse the average 11- and 12-year-old pupils, and so detract from the point of the exercise.
Then as a demonstration, possibly with pupils’ help, weigh the containers and complete the table.
What is the relationship between weight and size? Surprisingly, there is none. There is a heavy small and a light large container. It is not possible to predict weight from size or vice versa. So here is a case where there is no relationship between two variables. In order to
understand the notion of relationship, pupils must encounter examples of no relationship. This is the basis of ‘null hypothesis’ in science – it is easier to prove what does not cause an effect, than to make conclusive judgements about what the cause might be. (15 minutes)
6 Now give out the ‘relationship’ Workcard 1. Pupils can work in groups of three or four if they have been in pairs up to this point. For each picture they should determine:
- What are the variables (what are the things that vary)?
- What are the values of each variable?
- Is there a relationship between the variables? And if so, what sort of relationship?
Relationships can be described as ‘they go up together’, or ‘one goes up while the other goes down’. Go around the class to deter wrong strategies. Some possible answers are given below, although there are plenty of correct alternatives. (5 minutes plus)
ANSWERS to Workcard
|The higher the flame, the more bubbles
The taller the candle, the shorter the holder
No relationship between egg size and spoon size
The more sausages, the smaller they are The more clouds, the fewer flowers