Plants Need Light - So What is Photosynthesis?
Lesson 4 of 5
Objective: SWBAT explain the process of photosynthesis and why plants need light.
This lesson aligns to Essential Standard 1.L.2.1, "Summarize the basic needs of a variety of different plants (including air, water, nutrients, and light) for energy and growth. In today's lesson, students will learn how the different parts of a plant have a function that support its basic needs for growth and energy. They will be exposed to the process of photosynthesis through media resources.
I post an Essential Question or two for each lesson that students also have in their journals. Today's questions are 'Why do plants need light? How does it help them grow?' Listen to my Explanation of Essential Standards and Essential Question for more information.
Access to the internet/YouTube
Science journals, pencils
Copy of Essential Questions and Vocabulary for each student
1 page card stock for each student (plus extras)
This lesson is heavy on vocabulary just because it is a complex topic, so my goal is to show the students photosynthesis in a simple way to make the vocabulary easier to understand. The key terms in this lesson are:
- photosynthesis - the process a plant uses to convert sunlight into cellulose
- cellulose - sugar
- oxygen - the gas that humans breathe
- carbon dioxide - the gas that plants absorb
To start this lesson, I say,
"We have learned the basic needs of plants. One of them is sunlight. Today, we'll find out what plants do with sunlight and how it helps plants grow!"
Then I show this quick song which will be an introduction to the vocabulary. The tune is fun and the message is simple - plants and trees use photosynthesis to change sunlight into cellulose (sugar) for the plant. The visual component includes the scientific information at the bottom of the screen, but I do not focus on that at all - just the message of the song.
After the song, I say,
"There are some really important vocabulary words in this lesson that you need to know. We are going to add those to our word wall. You have them already glued into your science journal on today's page".
Then I show each card with the word and definition already written on it and give the very short definition. I have two students who glue in our question of the day each morning and today they glued in the vocabulary words as well. I considered asking the students to write it in, but I want to make sure it is correct. Also, it keeps the lesson moving to just provide this for students.
To understand photosynthesis, students need to understand that each part of the plant (like leaves, stem) have a function that is essential to the growth of the plant. This supports Essential Standard 1.L.2.1, the basic needs of plants, because without the leaves, the plant would not get sunlight and would die. The basic level of understanding of this concept is for students to identify the parts of a plant. A more complex understanding is to determine what the function of each part does and to create a model to explain the functions.Making a model aligns to Science and Engineering Practice 2.
First, I pass out the card. I cut a file folder in half vertically and then trimmed each one to fit into our science journals. Another way to make it would be to fold a sheet of card stock - paper would be too flimsy.
Then, I say,
"Today we are going to make a simple model of the function of each part of a plant. On the front of your card, we are going to draw a large plant. What parts should we include?"
As students tell me to draw a flower, roots, stem, and leaves, which they know from their background knowledge about plants, I model how to draw the large, fairly detailed picture on the front of my Teacher Foldable Example. Then I say,
"Draw your own plant, using most of the space on your card and make sure you have all of the parts of the plant!"
Then, I show them how to cut the front piece of card only (not the back!) to make a 'foldable'. I do this by first telling them to draw a line right under the petals, then on top of the leaves, under the leaves, and where the soil is. I model in red on a card so it is easy for my students to see exactly what I mean. Drawing and then cutting directly on the lines isolates each part of their plant. This is a complex activity for some students who are still learning to follow directions, so I have lots of extra paper on hand! After we have all cut the front of the cardstock into flaps, I show them how to flip the top one over and write 'Petals' and then write what the function of the petals is. Then we flip over 'Stem' and write what the function of the stem is, and then 'leaves' and finally 'roots'. Some students take longer than others and as students finish I check for accuracy to make sure they understood today's objective. Here are some examples of student work: Student Foldable Example, Student Foldable Example 2, & Student Foldable Example - Inside.
We work together on the carpet today because I usually find it easier to make sure my students are doing accurate work when we are close together and I can monitor what they are doing. Watch as the students work on the carpet.
After we finish the cardstock models of the parts of a plant and their function, we draw a simple diagram of how a leaf conducts the process of photosynthesis. I show this picture of Photosynthesis to get us started and I model how to draw a diagram on the board as the students copy. Since it is a complex process, it is important to really consider how detailed to make the diagram because I want my first graders to understand it and not to create any misconceptions!
After we have drawn the diagram, I say,
"Who can answer our essential question for today?"
I listen to a few responses and we finish the lesson with a good understanding of the function of plant parts and how they support the basic needs!