Rainbow Day

Objective:
The students will describe how rainbows form.

Materials

• If it's a sunny day - a glass filled with water, a sunny window, white paper, or prisms (if available).
• A book about how rainbows form, such as All the Colors of the Rainbow by Allan Fowler.  Or use one of the following web sites for information; What Causes A Rainbow?, or About Rainbows.
• How a Rainbow Forms Worksheet

Procedure

1. Ask the students what the know about rainbows forming.  When do we see them?  Why do they occur?  Have the students make a hypothesis about why rainbows occur.
2. Discuss the 7 colors that make up a rainbow - ROY G. BIV.
3. If it's a sunny day, fill a glass with water and place it in a sunny window.  A rainbow may be picked up on a white sheet of paper angled below the glass.  This may be done as a teacher demonstration, or small groups of students may be given their own glass to experiment with, depending on the age.  Sometimes a mirror angled in the water can help to create a rainbow as well. Another option would be using prisms if they are available.  Then the students may experiment with the prisms in the sunlight.  Remind the students that the prisms are taking the place of raindrops in nature.
4. If it's not a sunny day, skip right to this step and read the selected book about the formation of rainbows.  The aforementioned web sites also offer good information which can be altered to the students' ability of understanding.
5. Once the information has been presented, ask the students if their hypotheses were correct.
6. Have the students complete the How a Rainbow Forms Worksheet.

Other Lesson Ideas

1. If possible, go outside on a sunny day, use a hose and create rainbows.  The sun should be at your back when spraying the water.
2. Have a more in depth lesson on rain and the water cycle.
3. Have a lesson on the light spectrum.
4. Have a lesson on light refraction (the bending of light).