Crabs: Living and Adapted

Overview

Today students will learn about crabs as living things by identifying where they live, what they eat, and how their bodies are adapted for life in their habitat. They will observe crab features (pictures, diagrams, and specimens where available), and classify crabs using simple observable characteristics.

Learning intentions

• Students will describe key facts about crabs, including habitat and diet.
• Students will explain how some physical features of crabs help them survive (adaptations).
• Students will group and classify crabs using observable features from a classification key.
• Students will use evidence from observations to justify their classification.

Success criteria

• I can name where crabs live and give examples of crabs’ habitats (e.g. shorelines, mudflats, or rocky areas).
• I can state what crabs eat and sort foods into categories.
• I can describe at least two adaptations of crabs (for example claws for catching food or protecting, legs for walking, or a shell for protection).
• I can use a simple yes/no classification key to classify crabs and explain why.

Curriculum links

• Structure and function of living organisms (UK NC Science, Biology): link body features to survival needs.
• Living things and their habitats (UK NC Science, KS1–KS2): recognise that living things can be grouped in different ways.
• Living things and their habitats (UK NC Science, KS1–KS2): explore and use classification keys to group, identify and name living things.
• Animals, including humans (UK NC Science, KS1–KS2): compare and contrast diets of different animals and group according to what they eat.

Lesson structure (60 minutes)

1. 0–8 min · Hook and prior knowledge. Teacher shows a crab image set and asks: “Where do you think crabs live, and how do they survive there?” Students quick-write 2 ideas in books, then share with a partner.

2. 8–18 min · Direct teaching: crab facts. Teacher delivers short, clear input: habitat (where crabs are found), diet (what they eat), and body features (how they are adapted). Students complete a teacher-led “Crab fact” table: Habitat / Diet / Body feature.

Key facts to emphasise:

• Crabs live in or near water, often along coastlines and in muddy or rocky places.
• Many crabs are omnivores, eating a mix of plants, algae, and small animals (such as worms or small shellfish).
• Crabs have claws (used for feeding and protection), strong legs (for walking sideways and gripping), and a hard shell (protection).

3. 18–28 min · Observation carousel. Teacher sets up 4 stations: (1) crab pictures with labelled parts, (2) a simple model or photo of claws/legs/shell, (3) diet cards (food pictures), (4) an adaptation match-up sheet. Students rotate every ~2–3 minutes, recording one observation at each station.

Student task prompts:

• “What do you notice about the claw shape?”
• “How might this help the crab in its habitat?”
• “Choose 3 food cards that could be in a crab’s diet and explain your thinking.”

4. 28–42 min · Classification key activity. Teacher introduces a class-made, simple yes/no classification key for crabs (for example: “Does the crab have large claws? Yes/No”; “Is it mostly brown/grey or bright red/blue?”; “Is it small or larger in size?”). Teacher models one example, then releases students.

Students work in groups of 3–4 to classify a set of 6 crab cards using the key. They must write:

• the steps they used (Yes/No answers),
• the final group name,
• one justification sentence: “We grouped these together because…”

5. 42–52 min · Adaptation linking (mini-claim). Teacher asks the class to pick one adaptation and link it to survival: “How does this feature help the crab live in its habitat?” Students complete a short “Because” sentence:

• “Crabs have __ because __, so they can __.” Example: “Crabs have claws because they help catch and hold food, so they can eat.”

6. 52–60 min · Assessment and wrap-up. Teacher runs a quick whole-class share: groups read out one classification decision and one adaptation link. Students complete a 3-question exit ticket.

Resources

• Image cards of different crabs with visible features
• Crab part labels sheet (claws, legs, shell, mouthparts, antennae if shown)
• Crab diet picture cards (plants/algae; small animals; shells/rocks if relevant)
• Simple yes/no classification key worksheet for crabs
• Observation carousel record sheets
• Access to a real crab shell or model (optional) or high-quality printed diagrams
• Exit ticket slips or mini-whiteboards

Assessment

• Formative during carousel: teacher listens for accurate observations (what they notice) and clear links to habitat/diet.
• Formative during classification: check group worksheets for correct key steps and justifications using evidence.
• Exit ticket (3 questions):
• Name one crab habitat.
• Choose two foods and say why they fit a crab’s diet.
• Write one “Because” sentence about an adaptation.

Differentiation

• Support: provide sentence starters (“I notice…”, “This helps because…”, “We grouped them because…”), and a partially filled classification key for some students.
• Support for SEN: allow observation from the nearest station materials; offer 2–3 pre-chosen key choices to reduce writing load.
• Extension: ask students to propose an extra classification rule (e.g. “number of claws visible”, “colour shades”, or “habitat shown in the picture”) and test whether it still groups correctly.
• EAL: use visuals heavily; encourage students to rehearse answers with a partner before writing; accept oral responses recorded by the teacher where needed.