Light, Shadow & Penumbra | Shadow Size, Light Paths & Fair Tests | Physical Science Unit | Grades 4–6

Light, Shadow & Penumbra is a no-prep, hands-on physical science unit on light and shadows: six differentiated worksheets in a 12-page student book, plus a 7-page teacher guide with a four-phase lesson plan, differentiation notes and model answers.

All you need is an LED flashlight, an opaque object, a screen and a ruler. Students keep the object-to-screen distance fixed, change only the lamp distance and measure what happens to the shadow. They sketch boundary rays, use two lamps to separate full shadow from partial shadow by counting which lamps reach each region, find the flaw in an experiment where two things changed at once, and take the idea outside to explain long and short shadows through the height of the Sun.

What's Included

• 12-page student book with six differentiated worksheets (Discover · Practise · Apply)
• Knowledge page with illustration and key text
• Image lab: describe, explain and link a picture to a key term
• Investigation and extension tasks
• Learning check, self-assessment and a personal learning route
• 7-page teacher guide: rationale, learning goals and a four-phase lesson (Engage · Explore · Practise · Reflect) with timings
• Differentiation and diagnosis notes for foundation, core and extension
• Model answers for all six worksheets and the image lab
• Print-ready PDF (A4; prints on US Letter with fit-to-page)

Worksheet Sequence

1. Observe a shadow — light travels in straight lines and an opaque object blocks it
2. Change distances — closer lamp, bigger shadow, with only one variable changed
3. Sketch light paths — boundary rays as a model
4. Two light sources — full shadow, partial shadow and fully lit regions
5. Experiment error — spotting a test where two variables changed
6. Shadows outside — long and short shadows and the height of the Sun

Students Will Learn To

• distinguish full shadow (umbra) from partial shadow (penumbra)
• investigate how the lamp distance changes the size of a shadow
• plan and interpret a fair experiment that changes one variable at a time

Perfect For

• Elementary and middle school science (Grades 4–6)
• Light and energy units
• Science fair and fair-test practice
• STEM labs with simple equipment
• Homeschool science

Why Teachers Choose This Unit

• A complete sequence, not a set of loose worksheets
• Every task has a written model answer
• Differentiated so the whole class works on the same goal with different amounts of support
• Illustrations used as discussion prompts, with facts checked against the text or a real model
• Plan 4–6 lessons and teach straight from the PDF

Created with AI assistance: ChatGPT (OpenAI) and Claude (Anthropic). All materials were reviewed and edited by a qualified teacher before publication.

Frequently Asked Questions

What equipment do I need?

An LED flashlight, an opaque object, a screen or wall and a ruler. A second flashlight is needed for the two-light-source worksheet.

Is it safe?

Yes, with the usual rule the unit repeats: do not stare into bright light or look at the Sun.

Does it teach fair testing?

Yes. Students change one variable, keep the others fixed, and diagnose an experiment where two variables changed at once.

How is it delivered?

As an instant digital download after checkout. Nothing is shipped.