Frog Systems and Form

Overview

Today students investigate how external and internal structures in a frog relate to the functions of body systems. Students will connect observations from a frog dissection to NGSS ideas about structure and function and to how animals obtain and transport matter.

Learning intentions

• Students will be able to describe major frog body systems and identify key structures involved in those systems.
• Students will be able to explain how a structure’s form supports its function in survival processes (breathing, circulation, digestion, and movement).
• Students will be able to use evidence from observations to construct scientific explanations.

Success criteria

• I can label or accurately identify major structures on a frog and match them to a system.
• I can describe at least two examples of “structure → function” for frog anatomy (with evidence).
• I can write a brief CER (Claim–Evidence–Reasoning) explanation using observations from the dissection.
• I can follow safety and lab procedures and document findings in a lab record.

Curriculum links

• Life science: Structure and function in organisms
• Life science: Matter and energy needed for life processes
• Science and engineering practices: Developing and using models, obtaining and communicating information

Lesson structure (45 minutes)

1. 0–5 min — Engage & safety Prompt: “What could you predict about a frog’s needs just by looking at its body?” Review lab safety (gloves, eye protection, proper tool use), and set norms for respectful handling and disposal.

2. 5–10 min — Learning targets + quick model Students preview a simple organizer: Body system → structure → function → evidence they expect to see. Teacher introduces the dissection question: “How does anatomy help frogs survive and perform life functions?”

3. 10–30 min — Guided frog dissection (station work) Students work in small groups at teacher-facilitated stations. They observe and document: external features and selected internal structures. Teacher circulates, prompts students to record structure names and functional guesses (for later CER writing). Emphasize structure–function links (examples: skin/respiration, heart/circulation, lungs vs. water exchange, digestive tract and nutrient processing, musculature for movement).

4. 30–38 min — Evidence share & quick check Groups complete a short “evidence table” in their lab notebooks:

• Structure observed: __________
• Function it supports: __________
• Evidence from observations: __________ Teacher asks 2–3 groups to share one structure–function pair; class compares and revises notes.

5. 38–45 min — CER writing (individual) + exit tickets Students write a brief CER using one chosen example from the dissection. Exit ticket: “One structure I observed is ________. Its function is ________. I know this because ________.” Collect for formative assessment.

Resources

• Preserved or prepared frog specimens appropriate for student dissection
• Safety goggles and nitrile gloves (per student or shared with clear disinfecting routines)
• Dissection kits (scalpel/dissecting tools) with teacher-managed sharps
• Dissection trays and absorbent pads
• Labeling tools: markers, pre-printed structure cards, lab handouts/diagrams
• Lab notebooks or worksheets for evidence tables
• Paper towels, disinfectant wipes, waste disposal containers (sharps and bio-waste as required by school policy)
• Timer and station sign-up sheet
• Optional: teacher slideshow or poster of frog anatomy to support labeling

Assessment

• Formative: lab evidence table and teacher observation of structure–function reasoning during dissection.
• Formative: individual CER at the end of class focusing on claim connected to evidence and reasoning.
• Exit ticket responses to check understanding of structure–function and accurate terminology.

Differentiation

• Support (scaffolds for all groups): provide partially completed evidence table starters; offer word banks for structure and system terms.
• Support for SEN: allow diagram-based responses (circle/label) instead of long writing; provide a checklist of required observations.
• Support for EAL: use sentence frames for CER (e.g., “My claim is… I observed… This matters because…”); allow first-language discussion before writing when appropriate.
• Extension (advanced learners): require an additional CER that compares two systems (e.g., how respiration supports circulation by supplying oxygen to tissues) and prompts students to address one limitation of the evidence (what they could infer vs. what they could not directly observe).

Extension (optional)

• Students can model an energy/matter flow pathway (oxygen to tissues; nutrients from digestion into circulation) using arrows on a class diagram, then justify each arrow with dissection evidence.