Lesson Plan of Shadows and Eclipses
General Science Grade V
Students’ Learning Outcomes
· Investigate that light travels in a straight line.
· Explain the formation of shadows and eclipses.
· Predict the location, size and shape of a shadow from a light source relative to the position of objects.
Information for Teachers
· Light is emitted from luminous and spreads all around.
· Light from its source travels in straight lines.
· When light is obstructed by an opaque object, it is blocked.
· As no light passes through the opaque object, so it casts shadow of that object.
· An eclipse is the shadow of either the Earth on the Moon or of the Moon on the Erath.
· There are two types of eclipses, lunar eclipse and solar eclipse.
· Lunar eclipse occurs when Earth obstructs the sunlight reaching the Moon.
· Solar eclipse occurs when the Moon obstructs the sunlight reaching the Earth.
· The size of shadow increases as the distance of light source from the o0bject decreases and vice versa. Due to this fact the shadow of object changes dramatically throughout the day.
· Shadow has the same shape as that of object.
Material / Resources
Candle, three small wooden pieces, book, shoe box, torch, pieces of hard cardboard, scotch tape, textbook.
Worm up Activity
· Do the following warm up activities to involve the students:
1. Ask the students. Have you ever seen a shadow? Most of them will say ‘yes’
2. Select three students. Ask one of them to paste a white paper on the wall with scotch tape.
3. Ask the second student to throw torch light on that white paper.
4. Instruct the third student to place his hand in the path of torch light. Now ask the student: What do you see on the white paper?
(Expected response: Shadow of hand)
5. Ask the third student to change the shape of his hand and ask other students to observe.
6. Conclude the activity and tell the students that the shadows of the objects have the same shape as those of the objects.
· Bring three cards A, B, and C, three wooden blocks, a nail, scotch tape and a torch in the class.
· Make a small hole with the nail at the center of each card.
· Attach the cards on one side of each wooden block with scotch tape to keep the cards in vertical position.
· Ask a student to light a candle and place it in front of the hole of a card A.
· Ask another student to adjust card C so that the flame can be seen through its hole.
· Instruct him / her to place card B in between cards A and C.
· Guide the students to adjust the cards so that flame can be seen through all the holes.
· Ask the students: if card B is slightly disturbed, what happens?
(Expected response: No light is seen)
· Ask the students: Why flame is not seen from card C.
(Expected response: because light travels in a straight line, the three holes A, B, C are not in a straight line.
· Now tell the students that when holes are not in a straight line light can’t pass through the holes. Thus we conclude that light travels in a straight line.
· Bring a big ball (like a football), a small ball, a table lamp / torch and a marker.
· Select a place in the center of class and direct the students to sit around it.
· Ask a student to hold the torch at a suitable position and turn it on.
· Instruct a student to mark with marker on the big ball and show it to the whole class.
· Ask him to hold the big ball in his hands such that the mark faces the torch.
· Direct another student to hold small ball in a position between light and the big ball. Help him to adjust the small ball such that its shadow falls on the mark.
· Inquire the students: Can you see the mark on the big ball clearly?
(Expected response: No)
· Ask them: Why the mark is not clearly seen now?
(Expected response: : because small ball has blocked the light of torch to reach at the mark on big ball.)
· Ask them to consider the torch as the Sun, small ball as Moon and big ball as the Earth. As sunlight is blocked by the Moon to reach the Earth so it is solar eclipse.
· Ask them: Can you see the torch (Sun) if you are living in the marking (city) on the football (Earth)
· Explain them that as small ball (Moon) obstructs the light (sunlight) so city becomes dark and you can’t see the bulb(Sun) directly
· Ask the students: How can a lunar eclipse be produced from this arrangement?
(After this response tell them that in lunar eclipse, shadow of Earth falls upon Moon.
· Conclude the activity by explaining the positions of the Sun, the Earth and the Moon during solar and lunar eclipses.
· Fix a stick vertically on a table with the help of plasticine. A as shown in the figure below.
· Ask the students to observe the position and length of the shadow of stick.
· Ask them to shine the torch at the stick position B, C, D and E. ask them to observe the size of the shadows formed at different positions.
· Ask the students to draw the stick and its shadow formed at different positions of the torch.
Position of torch
Diagram of the position and length of the Shadow of Stick
· Ask them to infer from their observations, the reason for different positions and length of the shadows.
Sum up / Conclusion
· Light travels in straight lines.
· All opaque objects are light blocking and cause shadows.
· When Moon lies between Sun and Earth then solar eclipse occurs.
· When earth lies between Moon and Sun then lunar eclipse occurs.
· Location and size of shadow could be changed but its shape is retained.
Ask the following questions:
1. If light could turn around objects, what type of shadow will be obtain
2. Have you ever raced with your own shadow? Who is the winner?
3. How can you change the size the shadow?
4. On what side of the object, its shadow is formed?
5. What is the name of eclipse which can be observed at daytime only
· Ask the students: in what ways did early people measure and tell time before the clocks were inverted?
· After the students’ response tell them that early people used directions and lengths of shadows to tell the time.
· To elaborate this give them an example of the shadow of a tree which changes its position all the day