Science at key stage 3    (Year 9)

• Present pupils with a range of questions, which could be related either to one attainment target, eg materials and their properties, or to one area with links to all three attainment targets, eg water. Ask pupils to suggest other questions which they might ask in this area and compile a list of questions, eg
• How much of an apple is water?
• Why do elephants throw water over themselves?
• Are waterfalls beautiful?
• Are the types and abundance of plants on the school field affected by the level of moisture in the soil?
• How could you classify all the plants that grow in and around water?
• What is the best way to clean dirty water?
• Which gases dissolve in water?
• Where is the rainiest place on Earth?
• How does the concentration of salt in a solution of salt water affect buoyancy?
• Ask pupils to identify which questions would be suitable for scientific enquiry, eg How much of an apple is water?, and which would not, eg Are waterfalls beautiful?
• Ask pupils to discuss briefly the strategies they would use to tackle these questions, and ensure that pupils recognise that there is a variety of strategies for answering scientific questions.
• Ask pupils to select a question for further scientific investigation.

• Help pupils to work out a technique for determining dry mass, using either secondary sources or preliminary work, eg leaving a slice of apple in an oven and weighing it at regular intervals until the mass is constant, trying different oven temperatures and different time intervals for weighing.
• Ask pupils to consider the available apparatus, identify the hazards and decide what they would need to do to minimise the risks from each of these.
• Help pupils to decide how to calculate the percentage of water in an apple from the dry mass of a slice.
• Ask pupils to carry out procedures safely and effectively, record their data and carry out the calculations needed to determine approximately how much of an apple is water.
• Ask pupils to evaluate the method used and identify ways in which their results may be inaccurate, eg water vapour may be reabsorbed if the apple is left to cool in the air and a desiccator is not available; the apple may not be of uniform composition; substances other than water may have been driven off, and to consider how many measurements they would need to make to have confidence in their results.
• Ask pupils to explain the significance of the amount of water in an apple by using their knowledge of the ways in which water is used by plants and in plant cells.

• Introduce the idea that elephants throw water over themselves, eg by using a video clip, and tell pupils that one reason they might do so is to help them cool down. Ask pupils how they could use a model to test whether this could be true.
• Suggest pupils model/represent an elephant with a pop bottle filled with warm water, and ask them to decide a strategy for considering the effect of water evaporation on temperature, eg by comparing the change in temperature of two containers of warm water, one wrapped in damp kitchen paper and the other wrapped in dry kitchen paper. Ask pupils to use preliminary work to help them decide which apparatus to use for required accuracy, eg standard thermometer or temperature sensor and datalogger; what to measure, eg temperature of water in container at two-, five- or 10-minute intervals; and how to control factors, eg by considering the values for the starting temperature of water, the volume of water in the container and the number of layers of kitchen paper.
• Ask pupils to carry out procedures safely and effectively and to decide how to record their data, eg as line graphs showing cooling curves for the two containers.
• Ask pupils to describe the patterns shown in their data to explain what these show about the cooling of the two containers, and to relate the results to wet and dry elephants.
• Encourage pupils to consider the limitations of the model/representation of the elephant as a pop bottle cooling down in a classroom, by researching relevant information about elephants, eg approximate values for body temperature, body mass and volume, surface area of skin, temperature and humidity of their environment, and comparing it to similar information about the pop bottle in the classroom. Ask pupils to suggest other reasons why elephants might throw water over themselves.

• Help pupils to carry out useful preliminary work to consider whether a study will yield useful data, eg by identifying common species of plant found on the field, testing different areas to see if moisture levels are different. Consider other factors that might contribute to the effect, but which cannot be controlled, eg aspect, light levels, inclination, pH of soil, and how to deal with them, eg by noting other factors at each site.
• Ask pupils to collect data, making other observations where appropriate, eg differences in same species growing in different areas, to record information appropriately, eg in tables, and to identify and describe patterns in the data related to moisture, including qualitative observations.
• Help pupils to look critically at results to decide how strongly they show a trend, particularly in relation to sample size and the number of other factors that might affect the variety and abundance of plants on the school field.
• Ask pupils to interpret results in the light of their scientific knowledge, eg that competition for resources can affect the size of populations.

• Help pupils to use secondary sources to make a list of plants that grow in and around both fresh and sea water. Identify sources which describe enough relevant features of water plants to allow their classification.
• Ask pupils to plan an approach to classification which will discriminate between species, eg type of root/holdfast, method of reproduction, type of stem, to use their classification system to group similar types of plants together, and to use scientific knowledge to explain why some organisms share certain features, eg all those with holdfasts have to attach themselves to rock.
• Ask pupils to evaluate the strategy, eg how well it discriminated between groups, how well it worked for plants not on the original list, how often it was necessary to refine or extend categories.

• Ask pupils to consider what might affect the pH of rainwater, eg location, wind direction, volume fallen, time of year, weather pattern, and put forward a hypothesis.
• Ask pupils to consider why it is appropriate to use secondary sources to get information, eg it might not rain for several days, it would be difficult to collect enough data to identify trends using rainwater collected over a short period of time.
• Help pupils search for an environmental database on the pH of rainwater, eg on websites, on CD-ROMs or in reference books.
• Ask pupils to search for patterns in data, eg by considering whether pH is generally more acidic when wind is from the east, or whether pH is less acidic following stormy weather, to describe any patterns found and present the data they have used as evidence of these patterns.
• Ask pupils to look critically at the source of secondary data, eg
• Is the data collection carried out by volunteers?
• Is there data from some areas but not others?
• Ask pupils to identify the limitations of their own selection of evidence, eg
• I only looked at the link between wind direction and pH over 30 days. If I had considered evidence over a longer period I would have more confidence in my results
• Factors such as location and weather patterns may have affected the pH and I have not had time to investigate these
• All areas I had data about were in towns and cities; pH in rural areas might be different
• Help pupils to interpret results in the light of their scientific knowledge and understanding, eg oxides of non-metals such as sulphur and nitrogen are acidic, so when the wind blows towards us from countries with high emissions of these oxides, the rainwater is likely to be more acidic.

• Ask pupils to describe the different types of investigation used by themselves and others.
• Ask pupils to state and justify their conclusions and describe the limitations of their evidence. Encourage pupils to challenge each other's descriptions of the strength of relationships shown, and the quality of the data or the products.