Plastics and polymers: their structure and properties | 16-18 years

In this activity, polymers are used as illustrative materials for intermolecular bonds to help students to learn how the structures of polymers relate to their practical uses and properties.

Learning objectives

Students will understand that:

• Different types of intermolecular bonds exist.
• Monomers with different structures produce polymers with different types of intermolecular bonds.
• The structure of a polymer influences its use and properties.

Sequence of activities

Before the lesson

Prior to the session:

• Suggest that students bring in samples of any plastic material, washed and cleaned.
• Collect plastic samples yourself for use in the session.

Before students arrive, prepare seven ‘stations’ for sorting the plastics with name and recycling symbol number; the seventh will be for non-labelled plastics.

Introduction

Introduce the session by asking students:

1. To pool the samples of plastic in the centre of the room.
2. To look for the plastic recycling symbol present on many plastic items.
3. What the recycling symbol number means – check that they know.
4. To sort the plastics using the recycling symbol number.
5. Discuss which types of plastic are most popular.

Plenary

When all the samples are sorted, hold a plenary, asking, for example:

• ‘Which are the most common plastics amongst the items brought in?’
• ‘Why might these plastics be the most common?’
• ‘What are the different types of plastics used for?’

Tell the students that they are going to find out more about the most popular types of plastic.

Setting the activity

1. Give each student a copy of ‘Why do plastics have different properties?’.
2. Organise the students into groups of two to four.
3. Assign one or more plastic type(s) to each group.
4. Explain that they are to research and present a ‘research paper’ to be presented at a ‘Plastics conference’.
5. Agree criteria for peer assessment of the presentations that will be based on the information on ‘Why do plastics have different properties?’.

Conducting research and creating presentations

Circulate and support as groups:

• Research their plastic type.
• Prepare their presentation using an interactive whiteboard (IWB), data projector, OHP or paper poster.
• Elect one or more presenters.

Delivering presentations

Draw the groups into a plenary to:

1. Hear each presentation in turn.
2. Make their assessment of each other.
3. Discuss all the presentations afterwards.

Summarise the information learned about polymers, linking back to the pile of plastic ‘rubbish’ with which the session began, and invite students to make a written record of the information presented.

Commentary

This activity addresses the range of intermolecular bonds that should be known at advanced level.

The knowledge that they will be assessed by their peers and having agreed the criteria beforehand, gives students an added impetus to do their research properly. The process of creating a presentation forces students to make sure that they understand the key messages.

The written record permits formative assessment by the teacher. Written feedback gives the opportunity to support the development of understanding about the intermolecular bonds in plastics, where necessary.

Equipment

• Samples of plastics – these can be collected from everyday items that would normally be thrown away.
• Access to media to design the presentations; IWB, data projector, OHTs, poster paper and pens.