Understanding the greenhouse effect
The materials required for this science fair project:
- 4 transparent glass jars with plastic covers
- 4 thermometers
- An electric drill with appropriately sized drill bits
- 1 box of clay
- A stopwatch
- Tap water
- Sand for filling 2 cm height in the jars
- Black soil for filling 2 cm height in the jars
- Carpet grass for 1 layer in the jars
- 1 ruler
1. For this science project, the independent variable is the type of base used in the glass jar – water, sand, black soil and grass. The dependent variable is the temperature of the air inside the jar. This is determined by using a thermometer to measure the temperature. The constants (control variables) are the size of the jar, the external temperature and the amount of sunlight received.
2. Five jars are labeled as water, sand, soil and grass. The jars are filled with water (2cm deep), sand and soil according to the labels on the jar. A layer of carpet grass is placed at the bottom of the fourth jar.
3. Using an electric drill, a hole is made in the middle of the plastic covers. The size of the hole should the same as the diameter of the thermometer. The thermometer is then inserted through the hole on the cover. The base of the thermometer should be suspended approximately in the center of the glass jar, ensuring that it does not touch the surface of the water, sand, soil or grass. The clay is used to keep the suspended thermometer stuck to the cover. The cover is then placed over the jar.
4. The 4 jars are placed directly under the sun for an hour. A temperature reading is taken every 10 minutes and recorded in the table given below.
Adult assistance is required for operation of the drill