The Why Behind Teaching This:
Unit 3 addresses standards related to the transfer of energy and matter between organisms in an ecosystem. The unit begins with identifying what solar energy is and what two forms of energy solar energy provides to life on Earth. This is an important foundation for understanding standard 5-PS3-1: Use models to describe that energy in animals' food (used for body repair, growth, motion, and to maintain body warmth) was once energy from the sun. We build on this knowledge throughout the unit in other lessons related to photosynthesis and how animals use the energy they get from food. In this unit students will also be conducting experiments to gather evidence to support their belief that plants get the materials they need for growth from either water, air, or the soil. This is covered in standard 5-LS1-1: Support an argument that plants fet the materials they need for growth chiefly from air and water. Students will be creating food chains and food webs to describe the movement of matter among organisms in an ecosystem. This is covered in standard 5-LS2-1: Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.
I combined these three standards all into unit 3 because teaching them together allows students to see how they are all connected. The energy that plants get from the sun is stored in their parts until animals consume them. Plants cannot absorb this energy and reproduce without other materials from the environment such as carbon dioxide from the air, and water and nutrients from the soil. The animals that consume the plants use part of the energy for growth, reproduction, etc. but they also store some of the energy. That energy is then passed on to other animals once eaten. All of the energy that is available in an ecosystem can ultimately be traced back to the sun. Teaching all of these standards together, instead of in isolation of each other, makes that connection easier to see.
This specific lesson addresses standard 5-LS1-1: Support an argument that plants get the materials they need for growth chiefly from air and water. Through the multiple experiments that will be conducted, students will be collecting evidence to determine what is most important for plant growth. By working through the steps of the scientific method and controlling variables, standard 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.
The goal of today's lesson is for students to set up the four experiments and begin to gather evidence through experimentation to support their argument on what materials are most important for plant growth.
Students will demonstrate mastery of this goal by completing all four foldables in their science notebooks and collecting the first set of data for all plants.
Preparing for Lesson:
What Affects Plant Growth?
To begin today's lesson, I provide each table group with a Ziplock Bag with the Plant growth experiment - choice cards in it, precut. I write the question on the board: What material is most important for plant growth? I ask groups to discuss the answer to that question for a few minutes. The pictures I selected for the cards include sunlight, water, soil, and air. These are the items identified in the standard and the items that we will be discussing in the next several lessons about the parts of a plant and photosynthesis. I circulate to listen to conversations and to make sure that they are including the "why" in their responses to each other. I want to make sure they are supporting their reasoning with some things they already know about the topic. In this video of group discussion for what is most important for plant growth, the boy in the group is offering information about plants that he knows that do not live in soil and do not need much water such as cacti.
After a few minutes of discussions, and I have had time to make it around to all groups, I pass out a piece of construction paper to each group. I ask groups to create a poster on the construction paper with the item/items that they believe are most important to plants for growth. The choice card that they identified as the material that is most important should be glued on to the poster, then details added about their reasoning to support their choice. I do not require them to write it in paragraph form, they can, but do not have to. Some groups do write a paragraph explaining their reasoning, while others just create a list of their ideas.
Purpose of Creating the Posters:
I begin the lesson today with the posters for two reasons. One reason is to activate prior knowledge about plants and for me to get an idea of what background knowledge my students already have on the topic. Another reason is so that students will have their original thoughts on this topic recorded in some way to refer back to after the activity. Once the experiments are done, and evidence is collected, students will develop a new answer to this question and will be required to compare it to their original ideas and explain how their reasoning has changed.
Setting Up the Experiments:
In order to determine which item/items are most important to plants for growth, we are conducting four experiments simultaneously. It is important to conduct 3 trials for each experiment to ensure the results we get are accurate. Because this experiment entails a lot of set up, this portion will be done whole group, instead of each group doing it individually. Groups will however, be collecting their evidence independently each day.
All students get out their science notebooks to set up the four experiments together. I have the trifold boards of experiment steps copied for each student to save time. You can set up each of these experiments on separate days and take the time to write out each of the steps for each experiment if you choose. I provide the trifold boards one at a time and go over each step of the experiments together. Each experiment should only take about 8 minutes to go over as students do not have much to write, they are doing more listening then writing.
Testing How Water Affects Plant Growth:
I pass out the Experiment Steps - How Does Water Affect Plant Growth to each student. They title a page in their science notebook "How Does Water Affect Plant Growth" and glue their experiment foldable on that page. I read the question out loud to the class and ask the students what the independent variable (test variable) is for this experiment. They can easily identify this variable from the question and tell me it is water. Students close their foldable and record the independent variable on the front cover.
I move on to the hypothesis. After reading it out loud, I ask students to fill in what they believe will happen. I circulate to ensure that all students have the hypothesis filled in and to get an idea of what the majority of the class believes will happen.
We go over the materials and procedure together. While we go through the steps of the procedure, I show the materials that will be used at each step and model how each step will be completed. I stress control variables without pointing them out as control variables. For example, when we get to the step that says to place both plants in a sunny location, I say this is important because we are only testing how water affects growth, we don't want sunlight to have any impact on it. After going over all of the steps of the procedure, I ask them to identify at least four control variables. Students tell me the pot, the soil, the sunlight, the time measurements are taken, and the type of plant. They record these on the cover of the foldable where they wrote the independent variable.
The last thing we do is to review the data charts in the center of the foldable. Because there are three trials, two plants for each trial, I separated them into three charts. I feel that this will help make collecting the data each Friday easier for students. As we review the charts, I ask students what the data will be that is going to be collected. The tell me the height of the plant. I ask them what type of variable the height of the plant will be and they answer dependent variable.
Testing How Air Affects Plant Growth:
I pass out the Experiment Steps - How Does Air Affect Plant Growth to each student. They title the next page in their science notebooks "How Does Air Affect Plant Growth" and glue their foldable in on that page. We go over each of the steps just as we did in the above experiment. I point out each of the variables in this experiment and students record them on the front cover of their foldable. The independent variable is air and no air. The dependent variable is the height of the plant. The control variables are the type of plant, the amount of water, how often water is given, the type of water given, the pot it is planted in, the soil used, and the sunny location.
Testing How Soil Affects Plant Growth:
I pass out the Experiment Steps - How Does Soil Affect Plant Growth to each student. They title the next page in their science notebooks "How Does Soil Affect Plant Growth" and glue their foldable in on that page. We go over each of the steps just as we did in the other two experiments. I point out each of the variables in this experiment and students record them on the front cover of their foldable. The independent variable is the type of soil. The dependent variable is the height of the plant. The control variables are the sunny location, type of plant, amount of soil, clay, and sand used, the amount and type of water and how often it is given, the type and size of pot.
Testing How Sunlight Affects Plant Growth:
I pass out the Experiment Steps - How Does Sunlight Affect Plant Growth to each student. They title the next page in their science notebooks "How Does Sunlight Affect Plant Growth" and glue their foldable in on that page. We go over each of the steps just as we did in the other experiments. I point out each of the variables in this experiment and students record them on the front cover of their foldable. The independent variable is sunlight and no sunlight. The dependent variable is the height of the plant. The control variables are the type of plant, the type and amount of soil, the type and size of pot, the amount type of water and frequency they are watered.
Beginning the Experiments:
I have a student read step one of each of the four experiments from the foldable. Three of them are all the exact same, plant 2 plants in identical pots with the same amount of soil. The last experiment begins with planting three identical plants in equal amounts of soil, sand, and clay. I provide three groups with six identical pots, I just used plastic cups. I divide the fifth group up so by having each student join another group to help with the planting.
Before passing out materials, I model for the class how to correctly label their cups. I use the clay, soil, and sand group as an example since they have the most cups to label. I tell the class that trial 1 is going to have a cup of soil, a cup of sand, and a cup of clay. I take three cups and label them Soil A, Sand A, and Clay A with a permanent marker. I take three more cups and I tell them these cups will be for trial 2 and ask what they should be labeled. The students tell me Soil B, Sand B, and Clay B. I label them as indicated and then pick up the remaining three cups for this group. I ask what the last three cups should be labeled and they tell me Soil C, Sand C, and Clay C. I label them and place them back on the tray. I demonstrate how to remove the plants from their tray carefully and how to plant them in the soil so that every group does it the same.
I call over one materials manager for each group to get their materials. I have a tray ready that has 6 cups, a permanent marker, a tray of 6 plants, a cup of extra soil, and a spoon. One group also includes a 2 gallon freezer bag for the experimental group that does receive fresh air. One group receive 9 the nine cups I labeled with sand and clay as well.
As they begin planting, I walk around to ensure that groups are labeling and planting correctly. Group 1 is labeling their 3 cups with water A, B, and C and the remaining three cups with no water A, B, and C. Group 2 is labeling them as air or no air and A, B, and C. Group 3 as air or no air and A, B, and C. Group 4 already has them labeled.
In video 1 - planting plants, the group is labeling their cups and adding extra soil to their plants as they plant them. In video 2 - planting plants, two students in the group are adding sand to the plants and two other students in the background are adding the clay to those plants.
After all plants have been planted, the groups add 50mL of water to each plant except those that do not receive water.
Making The First Measurements:
Students place all plants on their tray and I provide each group with a ruler. I show them that they should be measuring from the base of the cup, to the tallest leaf on the plant. The group begins measuring the plants that their group planted, then they rotate around to each of the other groups to make their beginning height measurements. I am circulating to guide them through this first measurement to ensure they are recording their data in the correct location in their notebooks. After this guided measurement, they will be responsible for collecting their data on their own during the day on Fridays.
We then move all trays of plants to the window, except the one that does not receive sunlight. This plant is placed in the back of the room, away from sunlight.