Sink or Float Detectives

Overview

Students investigate whether familiar classroom objects sink or float in water. They make predictions, follow a safe procedure, observe carefully, record results using drawings, symbols or words, and compare their findings. This is an age-appropriate Foundation introduction to the Year 1 science inquiry expectations.

Learning intentions

• WALT make a prediction about whether an object will sink or float.
• WALT follow a safe investigation procedure.
• WALT observe, record and compare what happens to different objects.
• WALT share our findings using science words.

Success criteria

• I can say or show my prediction.
• I can use equipment safely and follow the steps.
• I can draw, symbolise or tell what I observed.
• I can compare my prediction with the result.

Curriculum links

• Science inquiry: asking questions, making predictions and participating in investigations.
• Representing observations and communicating findings using drawings, symbols, words and oral language.
• Australian Curriculum v9 Foundation introduction to Year 1 investigation learning, including identifying what happens in a simple test and considering safe use of materials and equipment.
• General capabilities: Literacy, Personal and Social Capability, and Critical and Creative Thinking.

Lesson structure (45 minutes)

1. 0–5 min · Engaging introduction. Open with the sink-or-float mystery slides and show a toy boat, a spoon and a block; ask, “What do you think will happen when each one meets the water?” Students vote with a thumbs-up for float or hands-down for sink, then share a reason with a partner. Suggested language: “A prediction is a careful guess. Scientists can make different predictions, and then we test them.”

2. 5–10 min · Safety and vocabulary. Show the investigation steps on the safety and procedure slides and explicitly model safe handling: carry the tub with two hands, keep water away from faces and electrical equipment, do not drink the water, keep objects out of mouths, and wipe spills immediately. Introduce sink, float, predict, observe, result, same and different. Students repeat the words with actions and identify the safe choice in picture examples. Teacher checks: “Where should our hands be?” “What do we do if water spills?” “Why do we test one object at a time?”

3. 10–15 min · Teacher modelling. Model the full procedure with one object: name it, make a prediction, draw or mark the prediction on the sink-or-float observation sheet, gently place the object in the water, wait, observe and record the result. Think aloud: “I predicted the wooden block would float. I can see it staying on top, so my result is float. My prediction matched my observation.” Students practise the sentence frame: “I predict ___ will ___. I observed ___.”

4. 15–32 min · Small-group investigation. Organise five groups of five students, with roles of object picker, predictor, tester, observer and recorder; rotate roles where practical. Each group receives a shallow water tub and a small set of clean objects such as a plastic lid, pencil, rubber, wooden block, metal spoon, cork, craft stick and small ball. Students choose one object, predict, draw or mark sink/float, gently test it, and record the result on the sink-or-float observation sheet. The teacher circulates, prompts careful observation and supports turn-taking. Ask: “What do you notice?” “Is the object on top or at the bottom?” “Did your prediction match?” “Which objects had the same result?” Avoid suggesting that heavy objects always sink; instead say, “We are collecting evidence to help us compare.”

5. 32–39 min · Compare and discuss. Pause testing, bring students together and revisit the compare-and-discuss slides. Groups hold up or point to their recorded results while the teacher creates a class display with two headings: FLOAT and SINK. Students compare results and notice patterns, such as some objects floating and some sinking. Discuss: “Which object surprised you?” “Did all groups get the same result?” “How can we make our test fair?” Reinforce that each object was placed gently in the same type of water and tested one at a time.

6. 39–45 min · Conclusion and assessment. Use the conclusion slides to complete the oral conclusion: “We found that ___ objects floated and ___ objects sank. We learned that a prediction is not always correct, so scientists test and observe.” Students finish the final drawing or circle on the sink-or-float observation sheet and tell a partner one prediction and one result. Collect sheets for assessment.

Resources

• Shallow, stable water tubs or trays, one per group
• Clean everyday objects with varied materials and sizes
• Water and towels or cloths for spills
• the sink-or-float mystery slides
• the sink-or-float observation sheet
• Pencils, crayons and clipboards or firm writing boards
• Optional photograph or tablet recording of group results

Assessment

• Listen for predictions that use “I think…” and observations that describe what actually happened.
• Observe whether students follow the safe procedure, wait for the result and distinguish prediction from observation.
• Review the worksheet for a recorded prediction, a drawing/symbol/word for the result, and a simple comparison. Confer orally with students who have limited writing.

Differentiation

• Support learners with object photographs, real objects to point to, two visual choices for sink/float, partner talk and sentence frames: “I predict ___.” “I observed ___.”
• Do not require independent reading. Read all instructions aloud, use large print and clear icons, and offer dyslexia-friendly options such as a plain sans-serif font, minimal text, strong contrast, uncluttered worksheet boxes, oral responses, drawing or adult scribing.
• Provide sensory choice for students who dislike wet materials: observe, predict, photograph or record results rather than touching water. Use a non-slip mat and carefully manage spills for students with mobility or coordination needs.
• For English as an Additional Language or Dialect learners, demonstrate each word with an action and object, rehearse vocabulary with a peer, and accept home-language discussion, gestures, drawings and oral explanations.

Extension

• Invite advanced learners to sort objects by material, size or shape and discuss whether these features helped them predict.
• Challenge students to choose one new classroom object, explain their prediction, test it fairly and draw a “because” statement: “It floated because…”
• Ask students to design a simple boat from classroom materials that can float, then test how many counters it can carry.

Take-home connection

Students tell someone at home about one object that sank and one that floated. With adult supervision, they may predict and test one safe household object in a bowl of water, then draw or describe the result. Remind families not to test electrical items, sharp objects or anything that could be swallowed.