Teach:
Discuss the items necessary for plant growth with your students. Students should know, water, soil, and sunlight. Ask them what they think will happen if salt is added to the water. Will the plants still grow or will they die? Ask the students how a plant could come in contact with salt? One example would be when salt trucks shoot salt to keep the roads from getting slippery and dangerous in the wintertime. Some of the salt can get on the plants and flowers on the side of the road. What happens to them?
Materials:
- Table salt
- Road salt
- Salt for a water filter system
- Plastic gloves
- Four jugs of water
- Measuring cup
- Four plants
- Notebooks
- Pencils
Discuss safe handling of road (rock) salt. Use protective gloves.
Procedure:
- Use four plants of the same variety for this experiment. With science and experiments it is important that you use constants. Every item should be the same and every measurement should be equal for a non-biased comparison.
- Place a label on each of the plants. They should be labeled clean water, table salt, road salt, and filter system salt.
- Choose students to participate in this part of the experiment. Leave your first jug of water alone. Pour out some water from the other three jugs. Add 1 cup of table salt to one jug and label it, add a cup of road salt to another jug and label it, and add a cup of water filter salt to the last jug and label it. Shake the jugs until all of the salt is dissolved.
- Set all of the plants in a sunny location and have students water them with the appropriate jug.
- Have students record what they have done so far into their science journals. Have students write a hypothesis their notebooks.
- Each day, record the findings into the science notebooks. What is happening to the plants?
- After three weeks report your findings.
- Have students write in their notebooks as to whether their hypothesis was correct or not.
Review:
Which of the plants survived? Which plants died quickly? Discuss the reasons why. How safe is rock salt to the environment? Extend this activity by soaking metal in the different solutions.
