Title: Investigating the Influence of Light and Gravity on Plant Growth

Introduction:
Plants exhibit various responses to external stimuli, including phototropism (the response to light) and gravitropism (the response to gravity). In this activity, we will observe and demonstrate how light and gravity affect the direction that plant parts grow in.

Materials:
1. Potted plant (e.g., bean plant)
2. Light source (e.g., desk lamp)
3. String or thread
4. Ruler or measuring tape
5. Sticky notes or labels
6. Marker or pen
7. Stopwatch or timer

Procedure:
1. Set up the potted plant in a well-lit area, such as near a window or under a lamp.
2. Attach a sticky note or label to the base of the plant stem, labeling it as "0 cm."
3. Choose a specific stem or shoot of the plant that you want to observe for growth.
4. Tie a string or thread loosely around the chosen stem, making sure it does not constrict growth but is secure enough to stay in place.
5. Mark the starting point on the string with a label, indicating "0 cm."
6. Using the ruler or measuring tape, measure the distance from the base of the plant stem to the starting point on the string.
7. Record the initial measurement in a data table.
8. Position the light source to one side of the plant, ensuring it shines directly on the chosen stem.
9. Turn on the light source and start the stopwatch or timer.
10. Observe and record the position of the stem every day for a designated period (e.g., 1-2 weeks).
11. Measure the new distance between the base of the plant stem and the current position on the string each day.
12. Record the measurements in the data table.
13. Repeat the same procedure with another stem, but this time, hang the plant upside down, so gravity acts in the opposite direction.
14. Analyze and compare the data collected for both stems.

Results and Discussion:
1. When observing the stem exposed to light, you should notice that the stem gradually bends or curves towards the light source. This demonstrates positive phototropism.
2. In contrast, the stem subjected to an inverted position (upside down) should exhibit negative phototropism, growing in the opposite direction away from the light source.
3. The measurements recorded each day will show the change in the position of the stem, indicating the influence of light and gravity on plant growth.
4. By comparing the two sets of data, you can conclude that light and gravity play a significant role in determining the direction in which plant parts grow.

Conclusion:
This activity allows us to observe and understand how plants respond to external stimuli such as light and gravity. Through the use of a labelled diagram and data collection, we can clearly see the effects of positive and negative phototropism on plant growth.