What Makes Things Visible?

Overview

In this first lesson of the Light and Matter unit, students investigate a dark-room phenomenon: some objects glow, some reflect light, and some become visible only when illuminated. They distinguish light sources from illuminated objects, use observations as evidence, generate investigable questions, and create an initial model showing light paths from a source to an object and/or eye.

Learning intentions

Students will be able to:

• Distinguish between a light source and an object that is illuminated.
• Use careful observations to describe how light affects visibility.
• Generate questions that could be investigated through evidence.
• Create an initial model showing a source, object, observer, and light paths.
• Explain the purpose of a scientific model and how it may change with new evidence.

Success criteria

• I can identify whether an object produces light or reflects light from another source.
• I can use an observation as evidence for an idea about visibility.
• I can write a focused, investigable question about light and matter.
• I can draw and label a model showing where light travels.

Curriculum links

• Reading science and technical texts: follow a multistep procedure accurately during observations and modeling.
• Reading science and technical texts: interpret and represent technical information using a visual model.
• Reading science and technical texts: determine the meaning of domain-specific terms such as source, illuminate, visible, and transparent.
• Writing science and technical texts: develop questions and begin a short research pathway around a scientific phenomenon.

Lesson structure (55 minutes)

1. 0–8 min · Quiet notice and wonder. Darken the room or use observation boxes, and display a glowing screen, a flashlight beam, a white card, a colored card, and an object that cannot be seen until illuminated. Open with the phenomenon hook and notice/wonder prompt. Students silently record or sketch at least two “I notice…” statements and two “I wonder…” statements on the light and visibility investigation sheet. Do not explain the phenomenon yet.

2. 8–18 min · Phenomenon observations. Review safety: use LED lights only, never shine a light into anyone’s eyes, keep walkways clear, and move slowly under supervision in a darkened room. In groups of four or five, students rotate through teacher-managed observations using flashlights, low-power lamps, opaque/translucent/transparent samples, white cards, colored cards, and the hidden object. Students follow the posted sequence, record what changes when the light source, object, or viewing position changes, and identify evidence that light reaches the eye. Return to the observation sequence and discussion prompts.

3. 18–30 min · Question formulation. Model turning a broad wonder into an investigable question, such as “What changes when the flashlight moves closer to the card?” Students independently write three questions using the frame “I notice ___, so I wonder ___.” Partners select one question that could be investigated by changing or observing one condition. Groups refine one question and post it in the appropriate section of a class question board: source, object/material, observer, shadows, or brightness. Invite students to use oral, written, or drawn questions.

4. 30–42 min · Initial model. Demonstrate a simple model with labeled symbols for a light source, object, eye, and arrows showing possible light paths. Clarify that a model is an explanation that can be revised, not a finished answer. Students create an individual model on the source-object-eye model page, then compare models in groups. Require each model to include a source, an object, an observer, arrows, and a brief explanation of what the arrows represent. Ask: “What evidence supports your arrows?” and “Where are you uncertain?”

5. 42–50 min · Question board and consensus. Revisit the model comparison and consensus questions. Groups share one question and one model idea. Class sorts similar questions and identifies questions that could be investigated with observations or measurements. Guide students toward the driving question: “How does light travel and interact with matter so that objects become visible?” Record competing ideas and unanswered questions in a parking lot for later lessons. Briefly define and revisit source, object, visible, illuminate, reflect, and transparent.

6. 50–55 min · Exit ticket. Students complete the final section of the source-object-observer exit ticket independently. They identify the source and illuminated object in a described situation, draw one light path to an observer’s eye, and write one question they still have. Collect models and tickets before students leave.

Resources

• the complete phenomenon-to-exit-ticket slide deck
• the light and visibility investigation sheet
• LED flashlights
• Low-power LED lamps
• Opaque, translucent, and transparent material samples
• White and colored cards
• Small object visible only when illuminated
• Darkened room or observation boxes
• Eye protection
• Chart paper, markers, sticky notes, and masking tape
• Class question board or whiteboard

Assessment

• During observations, listen for accurate distinctions between light sources and illuminated objects; ask students to justify claims with evidence.
• Check group questions for investigability and models for a labeled source, object, eye, and sensible light paths.
• Use the exit ticket to identify misconceptions, especially the idea that objects are visible without light reaching the observer’s eye.

Differentiation

• Provide picture-supported vocabulary cards, partially completed model diagrams, and sentence frames such as “The ___ is a source because ___” and “I notice ___, so I wonder ___.”
• Allow students to demonstrate thinking through drawing, pointing, oral explanation, or writing. Read directions aloud and provide a clearly lit station for students who may be uncomfortable in darkness.
• Pair multilingual learners with supportive peers and preteach source, visible, illuminate, reflect, and transparent using the materials themselves.
• Extend students by asking them to show separate paths from source to object and object to eye, or to explain how moving the source could change a shadow or bright region.

Extension

• Students photograph or sketch three light sources and three illuminated objects at home. They must not photograph people’s eyes and should label each example with a brief explanation.
• Students add one new question to the class question board and identify what observation or measurement could help answer it.