Investigation - Soil
Students will set up an investigation to determine the relationship between soil location and diversity of macros (the number of types of bugs). Through field observations, data collection, discussion, and lab work, students will come to a conclusion about which location has the most species of macros and which location has the fewest species. This work can then inform their next steps.
The Lesson Plan:
This lesson focuses on setting up an investigation in order to explore relationships within a soil ecosystem. Collecting data to answer an investigable question will allow for a deeper understanding of soil function, provide a common language for sharing data within a scientific community, and create further investigation questions to demonstrate the continual nature of the scientific process. This can also expose students to the micro-worlds that are around us without us noticing. When it comes to observing the different parts of an ecosystem, some parts are more easily observed than others. For example, what are the different parts of a pond ecosystem? Even without a microscope or any other special tools, you can see at Mac's Pond that there is water, there are reeds, ducks, etc. But did you know that in a handful of soil there is a whole functioning ecosystem? Using our observational skills, we are going to get a chance to observe up close some of the important parts that make up a soil ecosystem.
- Have students either list or draw all of the living organisms they think live in the area where the group is. Generate a list as a group of all the organisms they came up with individually and write them on a white board or on butcher paper.
- Compost Food Web
- Scientific Drawing & Watercolor Activity
- Read a book about the Soil like Diary of a Worm or Under One Rock
- Allow students to free explore the garden and soil. What do they notice?
- Walk the cycle of compost- eat lunch, whole group takes food to compost and trash in kitchen, explain that kitchen compost goes to the Earth Flow, visit the Earth Flow & explain how it goes back into the garden, visit the garden & explain how compost helps plants grow, that food then goes back into the kitchen. That is a simple cycle that they can see and is applicable to them.
The Investigation Question (Student Centered)
- Show students the question:
- What is the relationship between location and the number of types of bugs (macros)?
- Ask them to write the variables in their journal (p. 10 or 12)
- Ask students to write "location" at the top of the changed variable column. Write "Number of types of bugs" on the chart in the measured variable section.
- This is an opportunity to have a discussion with students about what a variable is and the difference between a changed and measured variable. Depends on what your goals are.
The investigation Procedure (Student Centered)
- Three location still need to be decided. If you're short on time- you can tell the students where the team is going. If you have time, allow students to pick three locations. Possible location choices: Earth Flow Compost, Garden Compost, Forest Soil.
- Divide the students into three groups. Give each group one trowel and one container to hold the soil. Let them know that they are responsible for gathering the soil when the team goes to their location.
- Gather the soil and return to the Learning Studio area outside of the labs. Students can sit on the bench to face the board with their journals and pencils out.
- Have a chart pre-drawn on the board to save time here. Tell the students to finish filling in their chart by adding the locations. While students are getting their materials and finishing the chart, instruct the chaperone how to set up the microscopes with samples in the lab. It is helpful if you have already pre-set up the microscopes so that the chaperone only needs to add samples to each one.
- While the chaperone is busy inside, continue instruction in the hallway.
- Now that students have their journal filled out, explain to them the difference between total number of bugs versus the number of different types of bugs.
- This can be done by drawing 3 triangles, 2 squares, and one circle on the board. Tell the students that each shape is a bug, and then ask them to tell you the total number of bugs (6). Follow up by asking them how many different types of bugs there are (3), and point out to them that they will be looking for the number of types of bugs.
- Before entering the lab, cover microscope etiquette with students.
Data Collection in the Lab
- Ask students to bring their journals into the lab and not turn on the microscopes yet.
- If students are moving between microscopes (3 scopes with each sample), let them know that they will have 2 minutes at each scope and that at the end of the time, they need to write their data in the chart in their journal. Then they will rotate to the left when you announce for everybody to rotate. Have them practice the rotation at least once so they understand.
- If students are not moving between microscopes (3 samples at each scope), let them know that you will announce when to switch samples and record information.
- Let them know to leave the lights on with each microscope- even when they finish looking through it. This will protect the bulb from burning out from constant on/off switching. All of the lights can be turned off at the end of the investigation.
- Let students turn on the microscopes and focus them for a few minutes before starting the time.
- You and the chaperone can walk around to assist students. Also, use a pipette to add water to any soil samples that may be drying out under the heat of the microscope (to protect the critters from frying).
- Once all of the data is collected (chart is completely filled out), have students turn off all microscopes and begin the clean up process. Cleaning up now offers a brain break, bathroom break, and clears the space of distractions.
- Write on the board everything that needs to happen and tell the students that they must work together to get it done. They can mark things off the white board as they complete them. (They can do it! It also encourages stewardship of space & saves you clean-up time)
- rinse all petri dishes & turn upside down in the sink
- wipe down the counters
- unplug all microscopes and gently wrap the cord around them
- cover all microscopes and move them to the garage area (outer spaces of the lab)
- Return all soil samples to the large containers
- put any macro sheets away at front of lab
- put away any materials used - like sticks for poking the soil, pipettes for adding water, etc.
Data Analysis & Conclusion
- Now that the space is clear and bladders are empty. Ask students to find the average for each location in their journal. You may need to explain how to find averages. Let them write the number however their teacher is covering math (2 remainder 3, 2.4, 2 1/2)
- Once they have the averages, they can write their conclusion statements:
- There are more types of bugs at (location) with an average of (average #) types of bugs.
- There are fewer types of bugs at (location) with an average of (average #) types of bugs.
- There are more bugs at the (location) compared to the (location) by an average of (differences between the averages) types of bugs.
- I think there are more bugs at (location) because there was an average of (average #) types of bugs there.
- I think there are fewer bugs at (location) because there was an average of (average #) types of bugs there.
- Once they have a minimum of two conclusion statements, make sure they show it to an adult who can review it. Send students back to make corrections as needed.
- Then they can find another person who has finished and compare conclusions. It is important that they understand that their conclusions are conversions of data into words- it is not a time for making inferences about why that specific data came out that way.
- Based on your data, what conclusion did you come to?
- Was this how you thought the investigation would turn out? What surprised you?
- If you could design your own investigation what relationship would you explore next?
- Why do you think these microorganisms live in compost?
- Why might it be important for so many different kinds of microorganisms to live in the compost?
- What did you learn that you didn't know before?
- What new questions do you have?
- Do you think you could find any of these organisms back at home? Where would you look?
- Have you ever found any of these organisms before? Where?
- Go back to an assessment piece if there was a before and after
- Consider moving forward with some of their questions for an upcoming lesson
- While students still have the microscopes and a soil sample, have them do a scientific drawing of one of the macros they can see.
- Scientific drawing can be done on page 18 of the journal or on a seperate piece of paper. Drawings can be done with watercolor if time permits.
- After students have finished their drawing and added as much detail as possible (number of legs, body shape, tail, etc), then they can get an identification sheet and try to ID their organism.
- Compost Food Web
Relevant Journal Pages:
- Investigation Planning and Charts, pgs. 8-12
- "Soil Organisms",pg. 18
- Investigation, Soil, Macro-invertebrate, Data, Conclusion, Evidence, Variable (Changed and Measured)