Wednesday, January 16, 2013

Living-NonLiving Lab Part 2

The richest discussions come from having to defend your ideas. For instance in biology, talking about what makes something “alive” can be a wonderful challenge for students in having them explain and defend why items are alive or why they are not. At first, it seems like an easy task, but we can provide samples that challenge student thinking, force them to address misconceptions and assumptions they have about how they view their world! Its in these discussions that wonderful learning takes place.

Ideas for Living-Nonliving Lab Stations: STEMmom.org


In a previous post, I share the details of a Living, Non, and Dead Lab that I love to do in biology classes. In that post, I describe the lab, how to set up stations, and provide a free download of the student lab. While I listed suggestions for what you can put at each station, I’ve had a lot of feedback on the stations that “trick” students. While tricking them isn’t really the point (albeit fun) we do want to provide samples that challenge their thinking. Therefore, in this post, I’d like to show you how to set up stations in this Living-Non-Dead Lab that will provide the richest experiences for your students.

Setting up Tricky Stations for Living/Non Lab: STEMmom.org

Choose your station items carefully. There are several ways to make stations "tricky."

  1. Pick easily identifiable objects that may cause students to leap to conclusions.  Items like seashells and corks make students pause before deciding whether they are living, non, or dead.
  2. Pick objects that are dead or hibernating. Dead bugs and seeds are great examples. Even better yet, choose the same items at different stages. For example, I like to have a packages of seeds at one station and at another some germinating seeds. It really makes students think.  
  3. Put objects into environments that they are not usually found. For example I put white rocks in paper towels in a beaker, trying to make students think they may be seeds. You could also put  items in a water bath or under a glass dome, or put something nonliving under a microscope. 
  4. Do something during the class session to a station to make students think you are feeding it to "keep it alive." Do this without fan fair, without saying anything out loud. Some students will likely pick up on this "care" and it will weigh in their decision of how to classify it! (Sneaky huh?)
  5. Slightly change it by changing its color or order.  I do this with my oil/water mixture. By adding a few drops of food coloring, I'm hoping some students may believe its undergoing photosynthesis. 

Tips for Setting Up the "Glue Monsters" Demonstration


One of the favorite stations I use for this lab is the “GlueMonsters—Are They Alive?” activity that comes from Flinn Scientific. While you could use this demo in isolation, using it with a combination of other stations gives students a wider view of how difficult it is to determine life.

Materials Needed for Glue Monsters Demonstration: STEMmom.org

Materials:

Petri dish (I used a mini mason jar)
Duco cement modeling glue
Construction paper and tape
Wood pencil shavings
Overhead projector
Tap water

Premise of the Glue Monster Demo


The glue is the “critter” and the pencil shavings are the “critter food.” You should keep the identity of the glue and shavings a secret. Therefore you will need to develop (and even practice) your technique so that at the time of the demo students don’t get a close look at these so they can identify the substances.

Remember: Don’t use the phrase, "Glue Monster" in front of your students! You don’t want them to know its glue! Its a "critter."

Setting up for Glue Monsters Demonstration: STEMmom.org

 

In preparation for the lab


Duco cement glue really is the only one that works reliably.  I looked at all the super stores and hardware stores around me, and couldn’t find it. I ended up buying it at Amazon. To keep your students from identifying the critter and the food, cover the glue tube with paper (or use a pipette to transfer it to the dish) and place the shavings in a non-descript dish.  If you are working with just a few students, you can perform this demo with them leaning in to watch the reaction. However, using an overhead increases the drama and allows students to only view a silhouette of the critters and food. The glue critter is more opaque when viewing with an overhead.


Prepping the Glue Monsters Demo: STEMmom.org

Once you have students attention, first add the "critters" to the water, then add the "food." Again, do you best to hid the identity of these items, and focus them on what is happening when the food is added. The glue moves solidifies a bit and moves around in the water. Sometimes it interacts with the shavings, and other times it just swims around. Here a a video of the Glue Monster's Demo. I have this posted on You Tube, without any reference to "Glue Monster." Feel free to use it if you don't have the time or resources to do the demo yourself. 


Living-Non-Dead Stations


The Glue Monster Demo is one of two stations that I do with students as a class. The other is the Sewer Lice (Raisin Dance)  These need to be done as a demo because the “critters” are only active for a short time, and you want to control how close students are to the sample. I usually number these stations 1 and 2. All of the other stations are located around the room. I tape a 3x5 card with the station number, and any special tips or instructions. Tips range from, mix the sample with the stir stick and waft the sample to smell it, or wave your hand near the sample and touch the sample to feel its texture. Students usually start at the lab table where they usually sit. So after entering stations 1 and 2 into their data tables, they will focus their attention to the station in front of them. That means most students will not be at station three. As they begin this first station, I usually rotate around the room, making sure they
enter their observations in the corresponding column. I also encourage them to write brief description of what is at the station in the table to help us when we are discussing the next day!  Then using a kitchen timer (great gift for a student/new teacher BTW) students rotate around the room, getting close to the samples as they mark their data tables. If some students work faster than others, I direct them to the post lab questions. 

I encourage science banter about what they are observing. However, I do not allow them to belittle one another for the observations they make (this can get out of hand if they are arguing what the samples are, rather than their characteristics). 



Keep Students Focused on the Characteristics


Too often students become obsessed with identifying the objects at the stations. Students believe identifying the samples will help them determine whether the sample is living, non, or dead.  In some cases that is right, but usually the time spent trying to identify objects distracts them from the purpose of the lab. The focus should be on the characteristics instead. 

Characteristics of Living Things (official ones):

  • Has cells
  • Grows
  • Can reproduce
  • Responds to the environment
  • Metabolizes
  • Maintains homeostasis
  • Made of organic molecules (proteins, lipids, carbohydrates, and nucleic acids)


While your students may not have come up with the official  characteristics, they've come up with a list by which they are vetting the items at the station. Therefore, if a student said that "movement" is a characteristic of life, instead of trying to figure out what the item is, focus them simply on the characteristics that they listed, like whether or not it moves. Inevitably, students will have chosen some characteristics that do NOT help them determine whether the items are living or not. I've had students begin the lab insistent that "having color" meant it was alive. Its fine for them to list traits that you know will not help them! One of the post lab questions will address how well their chosen characteristics helped them make their final decisions. (The entire lab is available for download in my first post about this lab.)  


The Big Ideas You Hope Students Figure Out 

The purpose of performing this lab as an inquiry experience, is that students will make the conclusions themselves. Here are a few you are hoping they reach:

  • It is not always easy to determine whether something is alive.
  • An item that is non-living, can never have been alive (hence the dead category).
  • Non-living items can have many of the traits of living things.
  • Simply observing without doing any tests make it difficult to determine whether it is alive.
  • Being able to kill, doesn't make it alive.

While you could easily just give students these big ideas in a lecture, it is much more powerful for them to discover them on their own by completing this lab. This is a low level of inquiry. (See my posts on What is Inquiry? and What Inquiry is Not.) Its ok if not all students come to all of these conclusions on their own while completing their post lab questions. These big ideas should all surface during small and whole group discussions, so all student will benefit. 

To Tell or Not to Tell...That is the Question


Day 1: (1/2 day) Prelab Discussion: Talk about characteristics and have students brainstorm the attributes they believe all living things have.  Don't give them the answers! 

Day 2: Lab Stations: Students rotate through the stations: Homework is the post lab questions.

Day 3: (1/2 day) Post-lab Discussion: Check for student completion, have students share their thoughts in small groups, then share with the whole group. 

Teachers always ask me whether or not I tell students what I had at each station. And truth is, some years I do, and others I don't.  If you have multiple sections of the same class, and several teachers performing the lab, maybe on different days, its just easier not to ever tell them! But be ready for them to pester you. However, sometimes its necessary to share the true identity of the stations, so they understand the deeper issues of identifying characteristics of life. Plus, for some, they need to know they were wrong, for their ego's sake. You know the type of student I speak of! For example, when I had both a seed and a rock in paper towels, I wanted them to note the differences and know that one was living and one was non-living. 

Notes for Homeschooling Families


If you are homeschooling, I would still work hard to keep the station identities a secret as you set up the lab.  It will be more difficult to do, but worth the effort! A great extension activity for this lab would be to have your older children design a living/non lab a younger group of children. To have them sift through the creative thinking as you did to set up to the lab is a sure way to be sure they've internalized what they learned. You could have them explain to you why they've chosen the item for each station.

Can you think of some "tricky" stations you could set up for this lab? Please share! 


Do you like this lesson??? See more on the Lesson's Page

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