Science and Technology K–6 · Years 1–2

How hard do you pull: dragging light and heavy loads

Working Scientifically only (NSW 2017); Forces can change the way objects move (NSW 2024); Science understanding, Physical sciences (ACARA v9)

Practical, model not builtLow risk

This site has no interactive model of its own. Where a step or a material names a Concept Studio model, simulation or tool, it has not been built; an external simulation a step names (for example PhET) is not part of this site.

The idea

A heavier load needs a stronger pull to move it across a surface, and how strong the pull is can be compared by how far it stretches the same elastic band.

What you need

A shoebox with a string loop through one end
A band puller: one 60 mm elastic band tied between the box's string loop and a card handle, with a card strip taped alongside it marked in equal steps, each step one paper clip long, so the stretch is read as a number of steps
Three identical books, each 400 g (weighed once); a wooden table top and a strip of carpet
Recording table: load, stretch to start moving (steps), stretch while sliding steadily (steps), three trials each

How to do it

Predict how the pull will change as one, two and three books are added.
Hook the band puller to the loop with the box empty. Pull slowly and note the step the end of the band reaches just as the box starts to move. Record it.
Keep pulling so the box slides steadily and note the step the band reaches now. Record it.
Put one book in the box and repeat. Then two books. Then three. Three trials each.
Move the box onto the carpet and repeat with two books.
Draw a picture graph: one square per step for each load.

What you should see

The stretch needed to start the box is a little larger than the stretch needed to keep it sliding, and both grow as books go in, so each added book raises the reading by about the same number of steps. The carpet readings compared with the table readings show which surface grips the box more. Because every reading uses the same band and the same card strip, the step counts compare with each other; they are not newtons, and turning them into a force is later work. The standard friction model behind the pattern is f = mu N, which the simulation on this entry runs: as a worked example there, with the wood-on-wood coefficients HyperPhysics reports for its own wooden surfaces (0.4 static, 0.3 kinetic), a 1.0 kg load needs 3.9 N to start and 2.9 N to keep sliding, and a cardboard box on a classroom table has its own coefficients. The learner knows it worked when the picture graph rises by about the same number of steps for each added book, and the starting reading is above the sliding reading for every load.

What changes

What you change: load in the box (0, 1, 2, 3 books); surface (table, carpet)
What you measure: stretch to start (steps); stretch while sliding (steps)
What you keep the same: same box, band and card strip
pull kept level and slow
three trials each

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Once something is moving it needs no pull to keep going on a table (friction keeps acting).
A heavy thing needs a stronger pull because it is bigger, not because of the surface underneath.

Safety card

Low riskLearners carry it out

Hazards

The elastic band snapping back

Controls

Pull slowly; the band checked for nicks before each use and replaced if worn; the band kept below eye level

Note

No chemicals or heat. Record the activity on the school's risk assessment (Primary School RiskAssess, Ecosolve Australia, riskassess.com.au).

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science and Technology K-6 Syllabus (2017), NESA. Current syllabus; NESA's timeline is 2026 plan and prepare, 2027 start teaching the 2024 syllabus. Code read from the official syllabus document on 2026-09-22.ST1-1WS-S
Science and Technology K-6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.ST1-SCI-01 ST1-PQU-01 ST1-DAT-01
Australian Curriculum v9AC9S1U03AC9S1I01AC9S1I02AC9S1I03AC9S1I04AC9S1I05

Sources

The pages the author read to write this activity.

All Concept Studio activities