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"Children should use enquiry skills in context. These up-to-the-minute stories will captivate them"

Anne Goldsworthy
Primary Science Expert

Topic: 3B Helping plants grow

Up to 4 million Malawians will not have enough to eat this year. Many interrelated reasons have caused this crisis in Southern Africa, including drought. In this activity, pupils make a chart to show how the yield of one important crop - maize - depends on rainfall. A new variety of maize may give higher yields when there is a shortage of rain. Students plan an experiment to see if the claims are justified.

Can science prevent famine teachers notes doc	science prevents famine activity

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· That crop yields depend on rainfall

Pupils will demonstrate this by creating a chart from data.

· Different varieties of the same plant need different amounts of rain to grow well

Pupils will demonstrate this by designing a fair test to compare the growth rates of two different maize varieties

Level 2
· Pupils describe the basic conditions that plants need in order to survive and recognise that living things grow
· Pupils, with help, make suggestions about how to collect data to answer questions

Level 3
· Pupils provide simple explanations for changes in living things, for example lack of water altering plant growth
· Pupils put forward their own ideas about how to find the answer to a question and recognise why it is important to collect data to answer questions

QCA unit 3b - helping plants grow
· Plants provide food for us and some plants are grown for this
· Plants need water - but not unlimited water - for healthy growth
· To use results to draw conclusions
· To decide how much evidence about healthy growth of seedlings is needed
· To suggest how a fair test could be carried out
· That in experiments and investigations involving living things, using just one plant in each set of conditions does not give sufficient evidence

Introducing the activity
· Display page 1 through a projector or as an OHT. Choose students to read the quotations aloud. If possible, show pupils some maize (corn on the cob) and some white flour made from maize (available as Italian polenta in supermarkets or as maize flour in health food shops).

Leading the main activity

· Give out copies of page 2 and describe the first task. This is to use the data to make a chart. Pupils can work on this in groups, or individually. A set of axes for the bar chart, as well as strips to cut and stick onto the graph, are available on page 3 if needed. The rainfall values are for 40-day periods during the growing season.

· Lead a discussion - either with the whole class or in small groups - to answer the questions posed by the woman on page 2. Suggested answers are:
o When the rainfall went up, more maize grew (up to a maximum of about 8000 kg/hectare).
o Either 100 mm or 125 mm of rainfall over 40 days gives most maize.
Students may need help to see that it makes no difference if you have more than 100 mm of rain.
o If 500 mm of rain falls, the yield is unlikely to rise above 8000 kg/hectare. The yield might even go down. Plant roots could become waterlogged - which stops the roots growing properly - or minerals could be washed away.

· Give out copies of page 4 to small groups. Lead a discussion to plan an experiment to compare the yields of two varieties of maize. Ask groups to complete the template with their ideas. This will be a challenging activity for many, so significant guidance is needed. Suggested answers are below. Please see the Word version of the teachers' notes for the answers formatted into a table.

We need to find out ... Whether the new variety gives more maize than the old one, when there is not much rain.
We will change ... The type of maize.
We will keep these the same to make it fair: · The rainfall.· The amount of light.· The type of soil.
We will plant __ seeds because ... More than one - 10-20 of each sort would be a good suggestion because plants don't all grow the same. If you planted one of each you could not be sure of the results. If you used more the tests would take too long.
At the end we will measure ... How much of each sort of maize grew.

· If time and resources allow, carry out a similar investigation. Different varieties of bean seed are a good alternative to maize, as they are easier to grow. Students will need to simulate rainfall by watering them at regular intervals.

· In the classroom students can control the water supply, but outside it is a different situation. The final question on page 4 gives able students the opportunity to consider this problem. It is claimed that the new maize grows better when there is a shortage of rain. This can only be tested at a site with a low rainfall. Students should choose villages A, B and C for their planned test, because they had low rainfalls in the past. They could then be asked to consider whether they can rely on the villages having the same rainfall in the future.

Oxfam
Background information to the crisis in Malawi

Oxfam
more details on crisis in Malawi - what happened to the crops, when are the best growing seasons and so on

Agricultural scientific journals
Tehcnical data on rainfall and maize yields

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