Beach clean-up

This task is about using evidence to support statements.

At a clean-up of rubbish at a popular New Zealand city beach 18kg of litter was picked up in one afternoon.

The table shows the percentages of different types of litter collected.

Type of litter	% of total litter picked up
Plastic 37% plastic sheet, including filters on cigarette butts 23% plastic foam 16% hard plastic	76
Metal	12
Paper	5
Glass	3
Other	1

Question 2Change answer

1. From reading the table, what can you say about the rubbish picked up? (Select one for each question.)

i) 76 pieces of plastic litter were picked up. TrueThere is not enough information to tell

ii) There was a greater percentage of paper picked up than glass. TrueThere is not enough information to tell

iii) Cigarette filters are made from plastic. TrueThere is not enough information to tell

iv) There were more beer cans than beer bottles left on the beach. TrueThere is not enough information to tell

v) Plastic litter is dangerous for crabs. TrueThere is not enough information to tell

Teaching and learning:

Nature of science idea

Tables are one way we can show scientific information. Tables can be:

an organiser for an investigation
a way of presenting data in a report
an organiser to assist comprehension and thinking.

Science concept
Materials have different properties. We choose materials because their properties suit the uses we put them to. The properties of materials also affect their impact on the environment when we have finished using them.

Why is learning to read tables important?
Tables can be useful tools for helping people make decisions. To do this, students need to understand the conventions of tables so they know how to read them. They also need to know how to critique the way data is presented. It is easy, if students are not skilful at reading tables, to interpret them incorrectly. They can make wrong decisions if they base them on false inferences.
Students often regard tables and graphs as an end in themselves. Few refer to them as a source of evidence, or as a way of exploring patterns and relationships in data or information. When deciding on an action, acting in a scientific way could involve gathering and analysing some data (i.e., gathering evidence) before deciding on actions to take to overcome the problem.
Read more about tables and graphs

Why is learning about rubbish important?
Disposing of our rubbish (or reducing the amount of rubbish we produce) is an environmental issue that concerns all of us, including young people. It is one that students can become practically involved in. The context of rubbish at the beach is one that many students are familiar with, having either witnessed or contributed to the problem, or been involved in a similar cleaning up activity. As students should be investigating issues of importance to them, it is preferable that they explore rubbish issues in a context that is relevant to the area they live in.
Knowing about the properties of the materials our rubbish is made of is central to making decisions about dealing with the problem. Collecting rubbish is a reactive rather than proactive response, but can be the first stage to investigating the issue, especially if students are encouraged to examine the patterns of what is collected and how it affects the environment, and use this data to suggest other actions.

Key competencies
This resource has direct links to the key competency, Using language, symbols, and text. Tables involve specific text conventions that are not exclusive to science, but they are commonly used to present scientific data.

Diagnostic and formative information:

In this task, Year 6 students:

Were more likely than Year 8 students to be distracted by their own background knowledge when reading the table, e.g., nearly half of them said it was true that the table provided information that told them plastic litter was dangerous to crabs, whereas about a quarter of Year 8 students chose this option;
Were less likely than Year 8 students to give multiple reasons for plastic being the most common rubbish collected.

Question a) is about interpreting data presented in a table. Question a) ii) is a straight forward reading from the table task, which most of the trial students were able to complete. However, they had much more difficulty when they had to:

Interpret the data on the table; or
Attend to details of the table, e.g., table headings.

The table below gives examples of both these challenges.

	Common response	Likely misconception
a) i)	True (about ½ the trial students in both years gave this answer)	These students are likely to have either not read the percentage sign, or not know what it means. In either case they have probably read the data as being 76 pieces of plastic rather than 76% of the total rubbish.
a) iii)	There is not enough information to tell (about 1⁄3 of the trial students in both years gave this answer)	It is likely that these students don't know that cigarette butts are made from plastic, and have either not read or not believed the given information. Students commonly ignore information that does not match their personal understandings. They also find it more difficult when they have to synthesise information from two different sources (in this case the details of the written text and the numerical values).
a) iv)	True (about ½ of the Year 6 and ¼ of the Year 8 trial students gave this answer)	These students may have inferred that beer cans and bottles made up the metal and glass components. However, there is no evidence in the table to either support or discount this.
a) v)	True (nearly ½ of the Year 6 and about ¼ of the Year 8 trial students gave this answer)	Students are using their own knowledge rather than the information on the table. The data does not provide any evidence to back up this statement.

The trial students did well at thinking up one reason why plastic might be the most common rubbish, but giving multiple reasons was more challenging. Some of those who did attempt to in fact gave the same reason in a slightly different guise.

Because there are so many things made of plastic and because they make so much of it
Because factories pack most of their stuff into plastic and because plastic is more popular than other litter types

It is useful for students to recognise that there are usually multiple reasons for a rubbish problem occurring, just as there are a variety of solutions.

Another response was to attribute the amount of plastic litter to people's habits without differentiating it from other types of rubbish.

Because people don't like picking up rubbish

Next steps:

For students who did not recognise the percentage symbol
Focusing on reading the table heading
Time should be spent focusing on the column titles on tables and discussing:

The information that will be in each column;
If applicable, the unit of measurement, and what this means;
Any symbols used (in this case %), and what this means (not just the word "percentage", but each number’s relationship to the total amount of rubbish).

Focusing on interpreting the % symbol in the overall context
If students have a good understanding of percentages, ask them to think about the following questions.

What information about the rubbish are we not given? (whether it is measured by weight, volume, or number of pieces). Are there any clues in the accompanying information?
Does how the rubbish is measured make any difference to the results expressed as percentages? (Students could carry out an investigation to answer this question, in doing so using a science context for mathematics. For example, they could sort some rubbish, count and record the numbers of individual pieces of rubbish in each group, record the weight of each category, and pack it into supermarket bags and count the number of bags for each category. They could then work out the percentage of each type of rubbish for each of the three methods. Are the answers the same?)
Why might it be important to know how the rubbish was measured?

For students who make inferences or are distracted by their own knowledge when reading data off a table

Ask students to provide evidence from the data to back up their answers.
What question did the people sorting the rubbish want answered? Why might they have asked this question?
Discuss the way that scientists work – that is, they gather evidence to answer their questions, but they also try to be very aware of not going beyond what the data is telling them.

(Note: Using what you know is also important in science, but students should be able to identify when it is appropriate to do this. For example, they might have very good reasons for stating that plastic is bad for crabs, but the table is not about this.)

For students who only give one reason for plastic being the most common rubbish at the beach
Students could work in small groups to collate their answers, putting each on a post-it. Each group's compilation could be combined to give a whole class overview. Similar answers could be grouped together. Students could suggest an overall category title for each group.

Follow up activities

Students could put the data into a graph, and discuss the advantages and disadvantages of tables and graphs. Which shows patterns better? Which is better to use for recording data as it is collected?
Students could carry out a similar investigation in their local area, using tables to record their results.
Peer assessment: Groups could be paired to critique each other's tables. They could develop their own criteria for providing feedback.
After exploring the trends in their collected data, students could use their analysis to suggest and prioritise actions (this links to the Participating and contributing Nature of science sub-strand).

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Beach clean-up

Beach clean-up

Question 2Change answer

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