Light Shadows and reflections
Objectives:
- To help children classify luminous and non-luminous objects
- To enable children to explore, visualise and identify difference between Transparent, Translucent and Opaque substances
- To provide an opportunity for students to observe, investigate, reason and infer
- To connect to children daily life experience of shadow formation and thus express using stories
- To help students understand and check their understanding about shadow formation
Process:
Resources:
Video (Aravind Gupta toys), Story - Shh! What's that? (PDF file), Simulation, worksheet and Materials for Hands-on activity.
Introduction:
- Begin class by asking students what are the things that they see in their surrounding, and how do they think they get to see those things? Can you see those things at night as well? Can you see those things when the lights were switched off?
- Discuss and introduce luminous and non-luminous substances.
Group activity:
- Divide children into 3 groups. Each group will have the following objects/materials: A torch, transparent plastic sheet, cardboard sheet, glass, plastic glass, wooden piece, pencil, notebook, piece of cloth, water bottle.
- Let each group see through the above objects/materials and pass torchlight through these materials. Let children document their observation in this table.
| Sl no | Objects/materials | Possibility of seeing through the materials/objects
(can see through/cannot seen through/partially seen) |
Allow/does not allow/partially allow light to pass through it |
| 1 | Transparent plastic sheet | ||
| 2 | Cardboard sheet | ||
| 3 | glass | ||
| 4 | Plastic glass | ||
| 5 | Wooden piece | ||
| 6 | Pencil | ||
| 7 | Notebook | ||
| 8 | Piece of cloth | ||
| 9 | Water bottle | ||
| 10 | Folder file |
- Ask students to group the objects in 3 groups based on its ability to see through them and allow light to pass through it.
- Encourage students to guess the name given to those materials/introduce the names of transparent/semi-transparent and opaque substances to students.
- Let students come up with their own definition for transparent/semi-transparent/opaque substances based on their observation recorded in the table.
- Encourage children to give examples from their surroundings to each of the categories and reason for the same.
Story reading:
Read a story, ‘Shh! What's that?’ and discuss the following questions with students:
- Have you ever experienced watching shadows? When?
- When do you think shadows will appear?
- How does the size and shape of the shadow varies?
- What are the necessary requirements for shadow formation?
- Can an object have 2 shadows? If yes, can they be of different lengths?
- What determines the length of a shadow/ what factors influence the length of a shadow?
- What determines the sharpness of shadows?
- Shadows are sometimes sharper and sometimes more blurred, why?
- Allow children to explore https://www.scootle.edu.au/ec/viewing/L756/index.html to understand more about shadow formation. Help children explore casting shadows and matching shadows section for a better understanding about shadow formation.
- Let children ask some of their questions related to shadow formation, encourage other students to think about answering to those questions, thus encouraging peer-peer interaction with sufficient guidance from facilitator.
Pin-hole camera making:
Let children make a model of pin-hole camera by referring to https://www.youtube.com/watch?v=mBPLL01mNjA,
Drag the cursor down on the above resource to get the complete view of it.
https://www.arvindguptatoys.com/toys/Pinholecamera.html.
Discuss the following questions with children.
- Why is the image seen in pinhole camera is inverted?
EA: Light from the top of the object after passing through the pinhole reaches the bottom of the camera screen, and light from the bottom of the object passing through the pinhole reaches the top of the screen. This causes the inversion of the image.
- What happens when the size of the hole in a pinhole camera is made bigger?
EA: When the size of the hole in a pinhole camera is made bigger, then the sharpness of the image obtained decreases. Also, the image becomes thick and blurry. This is because as the size of the hole increases, the amount of light entering the box increases, disturbing the formation of the image.
- Have you ever experienced or come across a pin-hole in nature?
