Flotation First Look

Overview

In this first lesson of the unit “Designing Safe Boats”, students begin by observing which objects float or sink in water. They develop early ideas about buoyancy and flotation through a hands-on investigation, making simple predictions and using observations to explain what they found.

Learning intentions

• Students will learn that water can push up on objects, which helps some objects float.
• Students will make predictions about whether objects will float or sink based on what they notice about the objects.
• Students will test predictions by placing objects in water safely and carefully.
• Students will share observations using simple science and design language (float, sink, push up, waterproof).

Success criteria

• I can predict “float” or “sink” before testing.
• I can test carefully and record what happens.
• I can describe that some objects float because water supports them (buoyancy).
• I can explain one match between my prediction and my results (even if it was wrong).

Curriculum links

• Te Mātaiaho Science (Fluids, resistance, and buoyancy) — Making and testing predictions about whether objects will float or sink in water, based on their properties.
• Te Mātaiaho Science (Buoyancy) — Buoyancy is an upwards force exerted by a liquid on an object.
• Technology for a design context — Exploring needs and wants through everyday problems (starting a “safe boat” idea by noticing what keeps things afloat).
• Key competencies: Thinking (making predictions), Participating and contributing (sharing observations), Using language, symbols, and texts (recording results with drawings/tables).

Lesson structure (30 minutes)

1. 0–5 min · Hook (story + question). Teacher tells a short “boat problem” story: “A boat needs to stay on the water—what helps?” and shows 2–3 everyday objects (e.g., spoon, stone, plastic lid). Students turn-and-talk to answer: “Which one do you think will float and why?”

2. 5–10 min · Direct teach (buoyancy for year 1). Teacher explains using simple words: “Water can push up on objects—this is called buoyancy. Some things float because the water’s push up helps them stay up.” Teacher introduces the investigation rules: dry hands for handling objects, careful placing, no splashing, and use only the designated water area. Students repeat rules and practise the action “place, release, observe”.

3. 10–20 min · Investigation stations (test lots of objects). Teacher sets up a “Float or Sink” station with a clear container of water and a tray of objects (assorted materials, including at least one waterproof item like a plastic block/lid and at least one sinker like a small stone; optionally one item that can change—e.g., a paper clip or sponge). Students work in pairs: choose one object, make a quick prediction card (“float” or “sink”), place it in the water, and observe. Students record with a simple table or sticker chart: object picture → float/sink.

4. 20–26 min · Share findings (class discussion). Teacher calls “spot the pattern” prompts:

• “What kinds of objects float?”
• “What kinds of objects sink?”
• “Did the water do something to the floating things?” Students share one result at a time using sentence starters: “I predicted ___ and it ___.” and “The water helped ___ because I noticed ___.”

5. 26–30 min · Quick exit ticket (individual). Teacher gives each student a small card with two blank boxes: “Next time I think ____ will float/sink.” Students circle float or sink for a new object shown at the end (e.g., a foam piece or a coin). Teacher collects cards for tomorrow’s planning.

Resources

• Large clear container(s) or tub(s) of water, with towels nearby
• Object set (assorted): plastic lid/box, sponge, cork or foam, stone/marble, paper, metal spoon/clip, small toy (ensure age-safe, no sharp edges)
• Prediction cards: “Float” and “Sink”
• Recording sheet: simple picture table or sticker chart
• Pairs’ object trays and tongs/spoons for safer handling (optional)
• Paper towels, spare dry cloths, aprons or waterproof smocks (if available)
• Exit ticket cards (one per student)
• Teacher sentence starters on chart paper

Assessment

• During the investigation: teacher listens for correct use of “float” and “sink” and checks that students make predictions before testing.
• During sharing: teacher uses quick prompts to confirm students understand buoyancy as an upwards support from water (at a simple level).
• Exit ticket: checks individual prediction skill for a new object and whether students can connect predictions to observations.

Differentiation

• Support: provide sentence starters (“I predicted ___.” “It ___.” “I noticed ___.”) and a pre-made recording sheet with object pictures.
• Support for confidence: allow students to start by choosing from a smaller set (2–3 objects) before joining the full tray.
• Extension: ask a challenge question for quick finishers: “What could we do to change what happens—keep it dry, wrap it, or use a different container?” (No building yet—just discuss ideas.)
• EAL/SEN: use visuals for float/sink, repeat key phrases, and allow drawing instead of writing for recordings.

Notes on safety

• Students work with water using clear rules; teacher or a responsible adult monitors closely.
• Objects must be age-safe, non-sharp, and suitable for water handling; avoid small items that could be a choking hazard.