Lesson 5 of 5
Objective: SWBAT understand that the shape of seeds determines their environment by creating a dichotomous key.
During this lesson, students will sort different kinds of seeds and then we will work as a whole group to create a dichotomous key for the seeds. The shape of the seeds determines how they travel. If seeds are hard and round then they drop and drop in that area. If they are fluffy and light, they get blown around by the wind and grow somewhere else. Sorting the seeds by physical appearance using a dichotomous key as a scientific tool will lead to a conversation about how seeds travel to find a place to grow.
This lesson supports Essential Standard 1.L.1.2, "Give examples of how the needs of different plants and animals can be met by their environments in North Carolina or different places throughout the world". Different seeds thrive in different environments and they have features that make them survive - such as being able to cling to things or to float on the breeze so that they can travel and have space to grow. By taking a closer look at seed by sorting them, students realize that the seeds are so different for a reason!
I teach the Essential Standards - Click here to listen to my Explanation of Essential Standards and Essential Question! Also, I post an essential question each day which is also glued at the top of the page in student journals. Today's question is "How do scientists identify different types of seeds? Why are seeds so different?"
To become familiar with a dichotomous key, look at the Plant Classification.
**As an alternative, this same lesson could be done with Leaves and Needles instead of seeds**
1 set of seed pictures per team (To make the seed pictures, I printed out multiple copies of the posters and cut the seeds pictures apart)
1 Large sheet of paper per team
To introduce the idea of a dichotomous key, I show this video. Sorting is nothing new to first graders, but the dichotomous key is, so after the video I talk about how it is used to help scientists and researchers to classify things. I say,
"Scientists use dichotomous keys as a way to sort things, like different species of animals or plants. Today, you will work with a partner to sort some seeds. Then, we will work together as one whole group to create a dichotomous key for different kinds of seeds to see how they are the same and different".
I chose to use a dichotomous key with my students for this lesson as a way to extend their understanding of sorting into groups. They can easily sort into 2-3 groups, but I want to show how scientists then look deeper and find other similarities and differences and sort within a group. Also, my school has a heavy use of graphic organizers and this is a great one to connect back to literacy!
"With a partner of your choice, sort the pictures I give you into groups. Then, glue the group together and label it. Try to make at least 3 different groups. You have 10 minutes!"
Students work in teams of 2 to sort the seed pictures, glue them in their groups, and label them. During this time, I provide very little help because I want students to reason with each other about how to sort the seeds. Recording the information about how they chose to sort the seeds and then sharing their pictures later in the lesson supports Science and Engineering Practice 4, Analyzing and Interpreting Data.
Sometimes I pick partners for students. For this activity, since it is short and also high interest, I am not too worried about students staying on task so I allow them to choose their own partner.
After everyone has finished their seed picture sorting, I call everyone back to the carpet with their science journals, pencils, and sorting page. I say,
"We are going to use the groups that you sorted your seed into to create our own dichotomous key. What is one way that you sorted your seeds?"
As I lead this conversation and create the dichotomous key, I want to make sure students understand that there may be more than one way to draw the key, but that I am just going to use ways that most of the students sorted.
After we have drawn the Class Dichotomous Key together, I say,
"The groups we made show the same kinds of seeds together. Why do you think these seeds ended up in the same group?"
After a few responses, I talk to the class about how seeds travel to find an environment where they can grow, and how the shape of the seed determines whether it will drop and grow in that same place or whether it will float or spin away.
To finish up this lesson, I say,
"Lots of you noticed how different the seeds are, and you used those differences to sort them into groups. Why do you think the seeds are so different?"
I want to make the connection that the seeds help the plant to survive, by growing more offspring - some seeds are light so they can travel, some have thorns so they will stay in that environment, etc. After a conversation with students about how the seeds are different, I say,
"Turn to you neighbor and answer the essential question for today - they were 'How do scientists identify different types of seeds?' and 'Why are seeds so different?'"
Communicating ideas and scientific information supports Science and Engineering Practice 8.