Arches, Stacks, Stumps

Overview

This is lesson 12 of 30 in the unit "Exploring Earth's Features" for Year 9 Geography, designed for a small class of 5 students. The lesson focuses on coastal landforms created by erosion — specifically arches, stacks, and stumps. It aligns directly with the National Curriculum for England KS3 Geography (Years 7-9), developing students' understanding of physical processes shaping the UK’s coastline.

National Curriculum Links

Geography Programme of Study (Key Stage 3) – Physical Landscapes

Locational knowledge: Understand and explain geomorphological processes shaping coastal features.
Place knowledge: Detailed study of UK coastal landforms including erosion features (arches, stacks, stumps).
Processes and skills: Explain physical processes such as erosion, weathering, and deposition; use geographical terminology confidently.
Key competency: Apply fieldwork skills (observation, sketching, description) and interpret physical features.

Learning Objectives

By the end of the lesson, students will be able to:

Describe the formation processes of arches, stacks, and stumps caused by coastal erosion.
Explain how different erosion processes (hydraulic action, abrasion, solution) contribute to these features.
Identify and label arches, stacks, and stumps on diagrams and UK coastal photographs.
Evaluate the changing nature of coastal landscapes and predict future development of these features.

Lesson Duration

50 minutes

Resources Needed

Whiteboard and markers
Printed labelled diagrams of coastal erosion features
High-quality colour photographs of UK coastlines (Durdle Door, Old Harry Rocks, etc.)
Individual mini-whiteboards or sketch pads for drawing
A rock sample or model to demonstrate erosion (optional)
Access to a prepared short 3D animation or time-lapse video showing coastal erosion (if digital device available)
Worksheet with sequencing diagrams and questions

Lesson Structure

1. Starter Activity (5 minutes)

Quick Quiz & Visual Prompt

Display images of an arch, a stack, and a stump on the board.
Pose rapid-fire questions: "What do you think these are?", "Have you ever visited such places?", "How might they have formed?"
Record student ideas on a mind map.
Purpose: Activate prior knowledge and contextualise the lesson.

2. Introduction & Explanation (10 minutes)

Teacher-Led Explanation with Diagrams

Define coastal erosion and briefly recap erosion processes (hydraulic action, abrasion, solution).
Explain step-by-step how sea caves enlarge into arches, arches collapse to form stacks, and stacks eventually weather into stumps.
Use annotated diagrams on the board and point to real UK examples (verbal references).
Highlight geographical vocabulary: headland, sea cave, arch, stack, stump, erosion, collapse.

Check understanding: Students label blank diagrams on mini whiteboards individually, then share with the class.

3. Activity 1: Sequencing & Role-play (15 minutes)

Interactive Group Activity

Give the class a set of labelled picture cards showing stages from cave to stump.
In pairs, they sequence the cards correctly and explain the process to the group.
Next, students role-play as ‘waves’ and ‘rock’, physically demonstrating erosion: one student pretends to be an arch while others simulate hydraulic action and abrasion to ‘collapse’ them into stacks and stumps (gentle movements to keep safe).
Purpose: Kinesthetic learning to reinforce understanding of physical processes.

4. Activity 2: Critical Thinking Discussion (10 minutes)

Predict & Evaluate

Present photos of a real coastal stack or stump (such as Old Harry Rocks).
Discuss as a class: "What do you think will happen to these landforms in the future? What factors will influence this?"
Encourage students to think about human activity, climate change, sea-level rise, and natural variability.
Students jot down their ideas on their work sheets in bullet points.

5. Plenary & Assessment (10 minutes)

Exit Ticket & Reflection

Each student writes 3-4 sentences summarising:
- How arches, stacks, and stumps form.
- Why coastal erosion is important to understand.
Rapid peer feedback using ‘one thing I liked, one thing I learned’ format.
Teacher collects exit tickets as formative assessment for understanding.

Differentiation

For less confident learners: Use step-by-step diagrams with simpler language, provide sentence starters for explanations.
For more able learners: Challenge with questions about rates of erosion and effects of human interventions on coastal change.
Visual and kinaesthetic learners: Benefit from diagrams, photos, and physical role-play.

Cross-Curricular Links

Science: Understand natural physical forces like erosion and weathering.
English: Develop precise geography-specific vocabulary and extended writing skills.

Homework Suggestion

Students research a UK coastal landmark with arches, stacks, or stumps, prepare a short presentation or poster highlighting its formation and current state.

Teacher Reflection Prompts

Did students grasp the sequential process of erosion forming arches, stacks, and stumps?
Which activities engaged students the most?
Were geographical terms used confidently in oral and written communication?
How might the role-play activity be improved for larger groups?

This lesson plan ensures active participation, rich geographical enquiry, and aligns precisely with the National Curriculum focus on UK physical landscapes, fostering both knowledge and curiosity in coastal geography.

Teaching Instructions