The ability to collect data by making observations and measurements during enquiries is the fourth skill area covered in this series of primary ‘scientific enquiry’ blogs.
Why are the skills of observing and measuring so important in scientific enquiries?
This skill strand lies at the heart of scientific enquiries. Observation and measurement is one way that scientists have to gain the data needed to test their predictions and to formulate new theories. For young learners starting their science education, discovering how scientists work and becoming young scientists in their own right, these skills will be crucial to develop.
Our youngest learners should be encouraged to observe objects and events and talk about what they see and experience. Then these obervations can be taken further, and comparisons can be made from them. Sorting and grouping activities (classification enquiries) are based on comparing objects or living things.
In a scientific investigation this comparison might be involve a series of tests. For example, the learner might be comparing which type of paper towel is most absorbent, based solely on observations of their efficiency in mopping up water. The comparisons can take the form of sequencing (‘This paper towel is best, this one is second and this one is third’). However, as soon as children have mastered the skills of measuring length, mass and time, the comparisons should be made in terms of numerical measurements
Measurement is linked to the scientist’s need to produce results that other scientists can check – hence, the use of standard units. Children should be measuring to the nearest marked division using simple instruments as soon as their numeracy skills are adequate.
What does progression look like in the skills of observing and measuring?
The ability to observe carefully, identifying which observations are relevant, and the language skills needed to express these observations will develop over time as literacy improves. At the same time, learners numaracy skills will develop and can be used in scientific enquiries when gathering data.
Learners will move from describing or responding appropriately to simple features of objects, living things and events that they observe:
- to observing and comparing objects, living things and events
- to starting to use simple equipment provided to make observations related to their enquiry
- to making relevant observations and starting to measure quantities, such as length or mass, using a range of simple equipment
- to making a series of observations and measurements that are adequate to answer the question posed in their enquiry
- to making a series of observations, comparisons or measurements with precision appropriate to the task
- beginning to repeat observations and measurements and to offer simple explanations for any differences encountered.
Remember that learners can observe, before they can compare, before they can count, before they can measure!
So in Stages 1 and 2 we should be teaching learners that it is important to collect evidence by making observations and measurements when trying to answer a question. We can start by exploring, using the senses of sight, hearing, smell, touch and taste as appropriate, and making and recording their observations, as well as any measurements taken.
As learners progress, they should be using simple measuring equipment and making systematic observations and measurements, including the use of datalogging if possible. Learners should also be checking observations and measurements by repeating them when necessary e.g. in enquiries where precise measurements are difficult to take, such as the height a ball bounces.
Progression in measurements is seen in greater degrees of precision and reliability as the children’s numeracy skills develop. The precision of measurement will be based on careful (scientific) observation of measuring equipment as readings are taken. For example, measuring the length of an elastic band to the nearest millimetre when investigating the effect of increasing the load.
Developing observation skills should begin as soon as young learners start school, where children should receive praise and encouragement for looking at things closely and noticing details. These young learners will develop into young scientists who will be keen to take precise measurements once they have the numeracy skills to deal with scales and decimal points.
Reliability can be thought of as the likelihood of getting the same reading if a particular test was repeated. Learners who can understand this concept, and have the numeracy skills to find the mean of a series of measurements, will be the highest attainers at the end of their primary education. They will also be able to suggest why there is any variation in the range of their repeated measurements.
So how can we develop the skills of observing and measuring?
Here are some strategies that we can use to develop observation and measurement skills in scientific enquiries:
STRATEGY 1 – Encourage careful observation
From an early age, learners respond positively to opportunities to look at things in close detail, using a variety of senses (warn of dangers of tasting!). Guessing games using ‘feely-bags’ or blind-folds are fun to develop the language of description and reinforce the fact that observation in science involves more than just ‘seeing’.
Nature walks are also excellent opportunities to encourage careful observation, and praise should be lavished on those who notice details that are not obvious. This promotes positive attitudes and learners enjoy the role of acting as a ‘young scientist’.
We can provide magnifying glasses to examine objects and living things. Young learners can soon pick up the technique of moving the magnifying glass back and forth until the object is in focus (although most using the equipment for the first time try to get their eyes as close as possible to the lens and object to make it bigger!).
This can be followed by the use of microscopes as soon as pupils have access to binocular models. This develops an attention to detail, as well as inspiring awe and wonder in the young mind. Youngsters who are used to scrutinising things closely will develop into precise measurers.
STRATEGY 2 – Start measuring!
As soon as learners are able to count, we can introduce the use of non-standard measures in their scientific enquiries. The skill of measurement gives learners access to more complex scientific enquiries. Non-standard measures prepare children for these investigations, and once they have started generating numerical data in their results, they can start developing simple graphical skills (See Recording and Presenting skills – to follow).
Our youngest learners can start to put things in order as a result of their enquiries. If they are investigating which ball is bounciest, they can say that the green ball was bounciest, followed by the blue one and finally the red one.
The use of non-standard measures is a ‘stepping stone between ‘making comparisons by observation’ and ‘making measurements using instruments’. In the ‘bouncing ball’ enquiry we can measure how high the balls bounce in a non-standard way by counting the number of tiles or bricks on a wall at the peak of the bounce. Alternatively, learners can use building blocks stacked up, or lengths of string / paper cut to the appropriate lengths, which are also great for displaying results!
Then we can ask questions that can stimulate progression. For example, “But what was the difference between the height each ball bounced?” or “I know you found that the green ball was bounciest, but was it much more bouncy than the other two? How could we tell someone else?” Some young learners will see the need for some form of measurement (although the more closed question, “Is there any way that we could measure how high they bounced?” can always be used if necessary).
As soon as learners can measure using simple equipment, they should always be stimulated to use standard measures. A learner’s decision to use standard measurement can be prompted by questions that raise the difficulties we have in sharing results using non-standard measures. For example, “If we took our results to another school, would they have the same size of tiles on their walls? Would they have the same building blocks as us?”
STRATEGY 3 – Check your results
Although the concept of reliability is a demanding concept, we can introduce it in an appropriate way as soon as learners start science. Results are reliable if someone else repeating our tests would be likely to get the same results. In Stages 5 and 6 this leads to repeat readings and calculation of means (averages). However, we can promote an early appreciation of the concept by asking questions such as, “If you did that again, do you think you’d get the same result again? Why don’t you try it?”
This is a useful technique in enquiries in which it is difficult to get consistent results e.g. bouncing balls (difficult to measure the peak bounce accurately) or cars on slopes (difficult to roll in a straight line!). This shows, at an appropriate level, that science doesn’t always provide clear-cut answers. It introduces uncertainty as an element of what could be termed ‘scientific literacy’ or ‘science for citizenship’.
Encourage learners in later stages to consider reliabilty. For example, having produced a table of results, ask the group to repeat one test again to see if they get the same result – highly unlikely (especially if you take their original table so that they can’t refer to it!). This stimulates discussion as to how we could make our results more reliable i.e. more likely to be reproduced by someone else following our method. Learners can suggest checking, repeating and averaging. For those without the numeracy skills to work out means, taking three readings, sequencing them, and then using the middle reading (the median) is a simpler way of improving the reliability of their results.
STRATEGY 4 – Teach the reading of scales
Many learners experience great difficulty reading the scales of some measuring equipment. Always use metric measures, and start with simple scales. However, more complex scales will need to be introduced progressively. This skill of understanding scales is also needed eventually in the graph drawing skills required to process the results of scientic enquiries. (See Recording and presenting – to follow).
Number-sticks are useful for modelling the vertical scales that learners will meet on thermometers and measuring cylinders. Use this strategy in your introduction to an enquiry, and explain the actual scale learners will see, before the learners use the equipment themselves. Lots of practice is needed in reading a variety of scales. Learners can design their own scales to challenge others in their group or you could ask them to produce a guide for a younger learner on how to use a particular measuring tool, which would include explaining the scale.
Simple data gathering exercises using a measuring instrument new to the learners will also help learners before expecting them to use it in the more demanding context of an investigation. For example, using a variety of force-meters to measure pulling forces in the classroom would be good preparation before using them to measure forces in an investigation into friction.
REFLECTION SECTION
- Do you have access to magnifying glasses and/or microscopes in your school? What age do you introduce the use of magnification to aid close observation?
- Are there any enquiries that you do with your class that could be differentiated in terms observation, comparison, and measurement using simple equipment?
Think of one enquiry in particular and outline the outcomes at different levels.
- If you were investigating different toy cars rolling down a ramp, think of some suitable non-standard measures you could use to express how far the car rolls?
- Have you got any children in your class who can sequence 3 numerical results then select the middle value (median)? Would this be a useful way to prepare children for higher level work in Stages 5 and 6?
- As part of your preparation for a science lesson, do you consider the scales that learners will meet on the measuring equipment used? How might that inform your lesson planning? Do you feel that any of the measuring equipment in your school is inadequate or inappropriate in any way? Do you need more measuring equipment to promote higher attainment in scientific enquiry?
- How would you respond to a child that insisted on using a stop watch, measuring to 0.01 seconds in an investigation into the dissolving of sugar?
- What do you say to the pupil who having rolled a car down a slope 3 times and got the results – 8 cm, 36 cm, 33 cm – adds them up and divides by 3 to get the mean? What might a pupil who had a deeper understanding of the concept of reliability do?