Salt Lamps and Plants

Objectives:
Today we will set up an investigation to see if a salt lamp affects plant growth.
We will use what we know about photosynthesis and cellular respiration to make sure the plants have everything they need in order to survive during the investigation.
At the end of the investigation, we will use results to discuss if/how the salt lamp appears to have affected our plants.

Materials:
Mint plant cuttings
- You will need to plan ahead to ensure multiple cuttings can be used for this lesson. A minimum of 10 is recommended.
Clear plastic cups
Sharpie to label cups
Salt lamp
Paper clips
Rulers
Articles for and against the health benefits of salt lamps
-Links are given in the lesson slides

Agenda (3 days)
Day 1:
*Introduce the idea behind the investigation
-Plants need to do cellular respiration and photosynthesis to live and grow.
-If inputs are missing for a process, the plant will eventually die.
-What do you think would happen if we add new possible inputs?
*Prompt possible connections between salt lamp and plant growth.
-These articles are about how salt lamps may or may not affect humans. Do you think it’s possible for them to affect plants? How? Why?
-Are these credible sources? Are these biased/unbiased sources? Why?
-What could we do to investigate the effects of a salt lamp on plant growth.
*Introduce the supplies for the investigation
-We have a salt lamp and some mint cuttings. Mint will continue to grow after it’s cut as long as it has water, oxygen, carbon dioxide and sunlight.
-What can we do with these supplies to set up an investigation.
-Ensure students remember every experiment needs to include a control group.
*Introduce investigation
-All mint plants will be put in the same type of cup with the same amount of water. All plants will be placed in a location with the same access to sunlight.
-Starting length and number of leaves present will be recorded for each plant.
-A control group will be left as is. An experimental group will be surrounding a salt lamp.
-After a specified amount of time (2 weeks min. recommended), plant length and number of leaves will be recorded.
-This is an opportunity to discuss independent, dependent and controlled variables.

Day 2:
*Set up the experiment
-Recall what was discussed the previous day about how the experiment will be conducted.
-Have students write an individual hypothesis for the investigation, and allow students to share their hypothesis with the class.
-Encourage respectful scientific arguments.
-Set up plants. Allow small groups to set up the plants.
- Create logs to record starting data. It is recommended to have a class poster to record data on, even students will be keeping individual logs. This will make it easier to discuss final results.
-Record initial observations.
-Number of leaves present on each plant and length of plants.
-Discuss how long the investigation will remain set up and when final data will be collected.

Day 3:
*Collect data
-Measure length of plants and number of leaves on each plant. Record data on class poster.
-Students should take measurements and compare the ending data to the start data to determine individual growth per plant and average growth for each group.
-Divide the plants amongst small groups to encourage all students to take part in the data collection.
*Analyze data
-Determine the growth in length and number of leaves for each plant.
*Discuss Analyzed Data
-This should be a student-driven discussion.
-What do you notice about the plant growth?
-What do you think our results mean?
-What new questions do you have?
-If time allows, discuss possible future investigations (experiments, research, etc.)