Do Leaves Turn Color All At Once? Part I
Lesson 11 of 14
Objective: Students will collect data and observe how leaves change color slowly
This lesson builds off of the lesson "Scientists Learn from Books and Media." The timing for this lesson depends on when the leaves begin changing color. Each year this may happen at a slightly different time (and in some places not at all..sorry). I begin this lesson when the leaves are just beginning to change color because the students gather data for a 2 week period.
The first day and last day of this lesson (see part 2 for the last day for data analysis) will take a full hour. The days in between should just take 20 minutes. I suggest going outside 3 times each during the 2 weeks of the study.
Building On Book Research
In a previous lesson students used books and media to find out about the process by which leaves change color. The results of the research was made into a short book that I begin today's lesson by reading. I want to begin by connecting to the prior knowledge that students have gained.
I praise the class for their hard work on the book and then ask, "do leaves change color fast or slow?" I let students vote for what they think. I say, "I am not really sure whether they change fast or slow but I have often wondered that. Do you think we might be able to find out by going outside?" I let students contribute their thoughts about when or how fast leaves change color. I encourage students to comment on each other's thoughts (encouraging meaningful scientific discussion among students by letting them know that asking questions about each other's ideas, or building upon someone else's idea is a way that scientists learn more from each other).
"It seems as if we are not all sure whether leaves change color all at once or slowly. How do you think we could figure that out?" (I want students to begin to play a role in the design of their own investigations so I encourage a brainstorm here. I can build off their ideas to design an observation study of how fast leaves change color. I write down their ideas on chart paper as they present them.) When we are done I say, "we have a lot of ideas here and I bet we could put some of them together to investigate how quickly leaves change color." (Here you will need to look at what students have said as you build the experiment. If a student says we can look at them you can turn that into observation. If someone says we could take pictures you can use that to talk about data collection.)
I want to introduce students to the design of an experiment in this lesson. I do not expect that they can design an experiment at this point, but what I hope is that they will be involved in brainstorming what we might do, and then I can use that to design the experiment. This is an introduction to how to design an experiment, and with practice they will be able to design an experiment to test different materials (2-Ps 1-1) because they have had experiences with what an experiment is.
The goal is to create an experimental design in which students will go outside and observe the leaves on a particular tree. They could document their tree by taking IPAD or camera photos to sequence, and they can pick up leaves below their tree and bring them in to press between wax paper to preserve the color in the leaf. They can also identify patterns in leaves that are changing. A big discussion in the classroom centered around whether leaves changed color from the center out, or from the edge in. Is there a consistent pattern to how this happens may become an extension of the lesson. As a teacher I think about what I want students to do, and then use their ideas to build my design. By doing this I am helping them to begin to design their own investigations.
Our Experimental Design
When the brainstorming is done I say to students, "you have some excellent ideas here now I am going to see if I can use your ideas to create the directions for our study. Does anyone know what a scientist calls the directions for the study? (if students do not know I tell them and write the words Experimental Design on the board. I also bring out the I Can statement for the day and show it to the students. It reads, "I can help design a science experiment." We read it together. I highlight the words design and experiment and point out how that is connected to the idea of experimental design.
I use what students have said to put the steps in order. I begin with the hypothesis step myself. I ask students what we might do when we first go outside and let them help me formulate the design. I want them to have an active role in the design, but this is a first time for students to use experimental design so I do not expect them to be able to design the steps on their own. With my help they are learning the components of an experiment and by later in the year they should be able to do this more independently.
"I am going to write out our design as a series of steps that we can follow." I type my steps on my computer which is connected to my Smart Board, but it would be fine to write the design on chart paper.
1. Make your hypothesis about how quickly you think leaves change color and record it in marker in your science journal.
2. Pick a tree where a few leaves have started to change color.
3. Take an IPAD photo of your tree with your name tag and date in the picture.
4. Look for leaves on the ground beside your tree and if one has changed color and is the same shape as the leaves on the tree, bring it inside.
5. On your recording sheet write the date and circle if you think a few leaves, many leaves, or all the leaves on your tree have changed color.
6. Collect data for 2 weeks.
7. Organize your photos in order.
8. Tell or show what you have learned.
"Does anyone see how long this experimental design will take?" (2 weeks). "Why do you think it will take 2 weeks?" (Because we need to watch the leaves change color) I ask for questions about the experimental design. I print out the page and ask students to place it in their science journals. (If you have handwritten the directions, you can just leave them posted in the room.)
Gathering the Data
I explain to students that we will begin by writing our hypothesis. "Do you remember what a hypothesis is?" (A good guess about what will happen). I ask them to finish the following statement in their journals. " I think that leaves on a tree change color _____________________ (quickly, all at once, slowly). I tell students they may pick one of my choices of words, or explain it in their own words.
"Ok now we will go outside. You and a partner will pick the same tree, or trees next to each other because you will need to share the IPAD cameras. You will take 1 picture of your tree holding your name tag with today's date in the picture while your partner snaps the picture. You will find one leaf on the ground with the same shape leaf that could have fallen from your tree, or if there are no leaves yet you will wait to do this. Look at your tree and decide if any, a few, most or all the leaves have changed color. We will record that in our journals when we come back inside. Can someone repeat for me what we will be doing?" I ask for a volunteer to repeat 1. pick a tree, 2. take a picture with your name tag in it, 3. look for a fallen leaf and 4. decide if a no leaves, a few leaves, most or all of the leaves have changed color."
We go outside to an area of trees and students look for a tree. I circulate around the area supporting students with their use of the IPAD and encouraging them to talk about what they are noticing.Engaged in Finding a Tree
When everyone has followed the directions we return inside to wrap up today's portion of the lesson.
Recording Our Data
I want each student to start a journal page to record their observations of the leaves on their tree. I ask them to glue the first journal page into their journal.
Once they are all glued I ask students to begin by recording today's date at the top of the paper. Now I say, "think about what you just saw outside on your tree. Think about how much of the tree had changed color today. In your journal circle if you think a few leaves changed color, some of the leaves changed color, most of the leaves have changed color or all of the leaves have changed color. There is a space below it to glue in your leaf. I will help you iron it between 2 sheets of waxed paper and then you can place it on this page. Also I will print out your pictures for you to glue in tomorrow morning when you arrive at school." (My students have a work time before school starts and so they will be able to glue in the pictures that I print out tonight.) "Right now you may write or draw what you noticed about your tree."
I give students 5 minutes to complete this writing/drawing.
It is important in science to give students a chance to talk about what they have learned or done each day. Today I bring students to the rug. I point to the I Can Statement which reads, "I can help design a science experiment." I ask, "how many of you feel that you helped to design the observation or experiment that we did today?" I wait for a thumbs up or thumbs down. "I think that your ideas helped us to design this experiment which is an observation of the trees outside. Are we done with our design yet?" I refer to the directions that we posted earlier so students can see that we need to repeat our work over the next few weeks.
"We do need to do this observation again don't we? We will need to go back outside and look at our trees every couple of days to see if there are any changes. We will keep our journals and record what we find for the next few weeks. At the end of the 2 weeks we will organize our data and try to answer our question, do the leaves on trees change slowly or all at once."
Note: If you are doing this lesson, you will need to repeat the gathering and recording data sections of this lesson several times each week for the next 2 weeks. At the end of the two weeks it will be possible to move to Part 2 of this lesson.