Lesson

Start of the project

Objective:

Determination of the unit of measurement of the parameter of objects;

Analysis and generalization of information;

Studying the change in shadow depending on the angle of incidence of light;

Establishing the relationship between light and shadow.

Performance time: 10-15 min

Teacher’s Guide

  1. Provide this material (PBL rubrics) for students to assess the project so that:

– students understand in advance what criteria they need to prepare for,

– students will be able to independently grade their peers accordingly.

  1. Before proceeding with the lab work, review the safety rules by following the link: safety rules
  2. Topic Guide:

– The Sun Rises in the East. As the Earth rotates around its axis counterclockwise, the sun appears to move across the sky.

– The sun sets in the West.

– The shadows get longer when the sun is low in the sky. They are longest at sunrise and sunset.

– Shadows are shortest when the sun is high in the sky. They are shortest at noon.

4. Click the link to download the worksheet for the practice activity: worksheet

Theoretical Part

Shadows are formed when light cannot pass through an object (opaque). Their shape depends on the shape of the object, the size of the object, the angle at which the object blocks the light, and the distance the object is from the light source. 

Light is one of the most important factors in the world around us. Scientists have calculated that light travels the distance from the sun to Earth in 8 minutes and 20 seconds. The sun’s light rays travel at a speed of 300,000 kilometers per second. When the rays reach Earth, they affect everything in their path. If the object on which they fall is opaque, the light cannot pass and a shadow is formed.

In the morning, the sun is in the east, so our shadow will be long and point west. As the day approaches noon, it gradually moves east as the sun moves west. At noon, the shadow is very short or nonexistent because the sun is above us. Then, as day turns to night, our shadow gradually moves west as the sun moves east.

Try observing the change in shade with a lab activity.

Practical part

Step 1.

Download and print the image shown below, or draw it yourself on an A4 sheet. This interactive model will help students understand visually.

Step 2.

Familiarize yourself with the necessary tools.

Step 3.

Fold or cut along the center line and glue along the fold of the science workbook.

Step 4.

Place the toy in the middle section.

Step 5.

Light the lantern on the edge of the sketchpad, like a sunrise. Show the sunrise and sunset, holding the lantern at the same level. Measure the length of the object’s shadow.

Step 6.

Observe the shadow of the object by capturing the light from the flashlight from different clocks. Measure the length of the object’s shadow at different times of the hour.

Step 7.

Fill in the resulting dimensions in a notebook in the form of a table.

sunrise9:0012:0015:00evening
… cm… cm… cm… cm… cm

Step 8.

Draw conclusions by answering the questions and write down your answers in your notebook:

How is the shadow formed?

Why did the length of the shadow change?

How did the shadow change over time: the direction of the shadow’s fall, the length of the shadow?

What type of research does this laboratory work belong to?

What methods of investigation did you use?

What unit of measure did you use to measure the object?

Conclusion

In addition to the fact that the length of the shadow varies throughout the day, it also varies in size according to the seasons. The tilt of the Earth’s axis affects the length of our shadows. In summer our location is tilted towards the sun, so our midday shadows are very short. In winter, our location is tilted away from the Sun, so our midday shadows are longer.

The students learned about shadow and its properties by doing practical work.

Reflection