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Science and Technology K–6 · Year 5

Pinhole camera: an upside-down image proves light goes straight

Science understanding: Physical sciences

Practical, model not builtLow risk

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The idea

Light from each point of a scene passes straight through a tiny hole and lands on the opposite side of the screen, so the image is inverted, and a ray diagram drawn to scale shows its size: halve the distance to the object and the image doubles.

What you need

  • a cardboard tube (a crisp tube) or a shoebox, 20 cm from pinhole to screen
  • aluminium foil for the pinhole end and a sewing pin
  • baking paper for the screen
  • black paper or tape to seal light leaks
  • an arrow 30 cm tall cut from black card and taped to a bright window, or a lamp with a 5 cm cut-out shape
  • ruler and tape measure

How to do it

  1. Cover one end of the tube with foil and pierce a pinhole in the centre; fit baking paper over the other end as the screen. Measure the pinhole-to-screen distance.
  2. In a dim room, point the pinhole at the arrow on the bright window from 3 m away (or at the lamp shape from 50 cm) and look at the screen.
  3. Describe the image: which way up, how sharp, how bright.
  4. Measure the height of the image and the height of the object and its distance from the pinhole. Record them.
  5. Halve the distance to the object and measure the image again. Enlarge the pinhole to 3 mm and describe the change.
  6. Draw the ray diagram: one straight line from the top of the object through the hole to the bottom of the image, and one from the bottom to the top.

What you should see

The image is inverted, dim and about equally sharp at every distance, and it grows as the object comes closer. Image height = object height x (screen distance / object distance): a 30 cm arrow at 3.0 m with a 0.20 m tube gives a 2.0 cm image, and at 1.5 m the image doubles to 4.0 cm, which still fits the screen of a crisp tube or a shoebox (a whole 1.5 m window at 3.0 m would make a 10 cm image, too big for the screen). A larger hole makes the image brighter but blurred, because each point of the scene now lights a patch, not a point; a very small hole blurs the image too, because light spreads as it passes through it (diffraction), so a hole about 0.5 to 0.6 mm across gives the sharpest image in a 20 cm camera.

What changes

What you change
object distance; pinhole size
What you measure
image height; image sharpness
What you keep the same
  • tube length
  • object height
  • room darkness

Common misconceptions

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

  • The hole turns the picture over like a lens does (straight lines through a point do it; there is no lens).
  • A bigger hole gives a better picture.
  • The image is on the hole, not the screen.

Safety card

Low riskLearners carry it out

Hazards

  • pin point
  • never aim the camera at the Sun and look in

Controls

  • adult pierces the foil
  • no Sun viewing through the tube

Note

Risk assessment before the lesson using Primary RiskAssess or the school's own template.

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), current, taught until 2026; a Stage 2 outcome, because NSW teaches the behaviour of light in Stage 2 ('investigate the behaviour of light', with reflection in a mirror and shadows as its examples), and neither the 2017 nor the 2024 Stage 3 content includes it; code read from the syllabus document on 22 September 2026ST2-8PW-ST
  • Science and Technology K-6 Syllabus (2017), current, taught until 2026; code read from the syllabus document on 22 September 2026ST3-1WS-S
  • Science and Technology K-6 Syllabus (2024), implemented from 2027; NESA's timeline is 2026 plan and prepare and 2027 start teaching, and schools may choose to implement it during 2026; code read from the outcomes page on 22 September 2026ST3-DAT-01
  • Australian Curriculum v9AC9S5U03AC9S5I03AC9S5I04

Sources

The pages the author read to write this activity.

  1. www.scootle.edu.au/ec/search?accContentId=AC9S5U03
  2. curriculum.nsw.edu.au/learning-areas/science/science-and-technology-k-6-2024/outcomes
  3. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
  4. spark.iop.org/pinhole-peeking
  5. spark.iop.org/pinhole-camera-and-lens-camera
  6. primaryconnections.org.au/teaching-sequences/year-5/light-imitates-art

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