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  • This Connected article by Ken Benn, looks at a class investigation into why they lost the boat float competition. It starts when student Meihanna asks “How come steel ships can sail across the ocean? Our boats are made of stuff that normally floats and they still sink!” Their initial boat design failures become a great learning opportunity.

    The students learn about an important science concept: density and how it is related to floating a boat, they critique their original designs and then incorporate their learning into new and more successful boat designs. The series of experiments and mathematical activities also introduce the concepts of mass and volume.

    Rights: Crown 2015

    Connected article: A sinking feeling

    An article in the 2015 Level 4 Connected journal, Is That So?’ published by the Ministry of Education, New Zealand.

    Illustration by Fraser Williamson.

    This article supports the science capability critique evidence – encouraging students to evaluate the quality of scientific data.

    Nature of science

    The Investigating in science substrand of the nature of science is the curriculum context for this article.

    Key nature of science ideas profiled are that scientists:

    • evaluate the trustworthiness of data by asking questions about investigations carried out by others
    • undertake more than one trial to provide sufficient evidence to support a theory
    • replicate investigations to critique the evidence or data provided by other scientists
    • check that there are enough samples to reliably establish a conclusion or theory
    • look carefully at the way data has been collected when they consider investigations done by others.

    Other key ideas

    Some of the other key ideas of the curriculum covered within this article include:

    • Science – an object floats if it is less dense than the water it is floating in.
    • Technology – the technologist considers the performance properties of materials when selecting them for a technological outcome.
    • Mathematics – organising data and looking for patterns and trends can reveal useful information.

    Check your school library for the article from the 2015 level 4 Connected journal ‘ Is That So?’, download it as a Google slide presentation fom Tāhūrangi or order it from the Ministry of Education.

    Rights: Crown 2015

    2015 Connected Is That So?

    The cover of the 2015 Level 4 Connected journal, Is That So?’ published by the Ministry of Education, New Zealand. This issue includes the articles: Reconnecting the brain, Lighting the way with solar energy, A sinking feeling and Don’t sit if you want to keep fit.

    Teacher support material and activities

    The teacher support material (TSM) can be downloaded from Tāhūrangi (Word and PDF files available).

    The Float my boat activity has been designed to support students to explore and develop understandings about the science capability ‘Critique evidence’ and to help with learning about the science concepts of density, weight and volume. Also included are some extension ideas.

    There are three activities linking to the technology curriculum.

    • Boat design – students design and construct a boat, taking into account factors such as buoyancy, the properties of materials and design constraints.
    • Buoyant boats – students explore the scientific principle of buoyancy through designing and constructing a simple tinfoil boat.
    • Boat designs over time – students learn about technological developments over time, this can include traditional boat building such as waka and speculations on future designs.

    There are also two activities incorporating parts of the mathematics and statistics curriculum. Literacy strategies also support students to understand, respond to, and think critically about the information and ideas in the text.

    Related content

    Explore the big ideas that underpin floating and sinking in this article. It is a partial replication of the Ministry of Education’s Building Science Concepts Book 37 Floating and Sinking: How Objects Behave in Water.

    Use these articles to further explore aspects of floating and sinking.

    The PLD article Physical World – Floating and sinking curates Hub resources on this topic.

    Check out our entire range of Connected articles here. We’ve curated them by topic and concepts.

    Our Floating and sinking Pinterest board is full of related resources.

    Activity ideas

    Will this float or sink? uses an interactive or paper-based graphic organiser to consider whether an object floats or sinks. Use it prior to a unit on floating and sinking to gauge students’ thinking and again during and after the unit as formative assessment.

    Investigating floating and sinking is a set of activities that use play and exploration to directly observe how everyday objects behave in water.

    Floating and sinking – exploring forces uses play and exploration to explore the support force (upthrust) that keeps objects afloat.

    Temperature, salinity and water density – use this activity to help your students visualise differences in water density.

    Floating eggs – students investigate water density by floating an egg in freshwater and saltwater.

    Buoyancy in water – students make a Cartesian diver to demonstrate the relationship between volume, mass and density.

    Useful links

    In TeachEngineering's Buoyant Boats activity students experiment to see how water levels change in a beaker when a lump of clay sinks in the water and when the same lump of clay is shaped into a bowl that floats in the water.

    Explore ships and boats and the science that enables them to float on the Explain that Stuff website.

    There is a range of questions and activities designed to get students to critique evidence under the Five science capabilities section on the Tāhūrangi website.

    Related Building Science Concepts books:

    Assessment Resource Banks

    The Assessment Resource Banks (ARBs) also offer a range of levelled activities that are ready for use in the class. You need to be registered to use ARB resources.

    The Connected journals can be ordered from the Down the Back of the Chair website. Access to these resources is restricted to Ministry-approved education providers. To find out if you are eligible for a login or if you have forgotten your login details, contact their customer services team on 0800 660 662 or email


    The Connected series is published annually by the Ministry of Education, New Zealand.

      Published 11 October 2022 Referencing Hub articles
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