Summary
Overview
In this small group activity, students will build a plant seed (burr) from a Styrofoam® ball and other crafts materials. The seed needs to be designed in a way that it can be dispersed by attaching to a mockup animal (wool glove). Students will first test if their seed attaches to the wool glove and then carry their attached seed along an obstacle course inside the classroom. As students design their plant seed and mimic its dispersal via an animal, they will realize how some plants grow specialized seeds and employ animals to disperse their seeds in order to increase their chances of successful reproduction.
Learning Objectives
- Name at least two modes of seed dispersal.
- Explain why plants grow seeds with hooks and spikes.
- Design and build a plant seed that fulfills certain requirements.
NGSS Alignment
This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:- MS-LS1-4. Use argument based on empirical evidence and scientific reasoning to support an explanation for how characteristic animal behaviors and specialized plant structures affect the probability of successful reproduction of animals and plants respectively.
- MS-ETS1-2. Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
| Science & Engineering Practices | Disciplinary Core Ideas | Crosscutting Concepts | |||
| Science & Engineering Practices | Constructing Explanations and Designing Solutions.
Apply scientific ideas or principles to design, construct, and/or test a design of an object, tool, process or system.
Undertake a design project, engaging in the design cycle, to construct and/or implement a solution that meets specific design criteria and constraints Optimize performance of a design by prioritizing criteria, making tradeoffs, testing, revising, and retesting. Engaging in Argument from Evidence. Evaluate competing design solutions based on jointly developed and agreed-upon design criteria. |
Disciplinary Core Ideas | LS1.B: Growth and Development of Organisms.
Plants reproduce in a variety of ways, sometimes depending on animal behavior and specialized features for reproduction.
ETS1.B: Developing Possible Solutions. A solution needs to be tested, and then modified on the basis of the test results, in order to improve it. There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem. |
Crosscutting Concepts | Structure and Function.
Structures can be designed to serve particular functions by taking into account properties of different materials, and how materials can be shaped and used. |
Materials
For each student group:
- Styrofoam® balls, 3 cm diameter (2)
- Wool glove
- Scissors
- Tape
- Glue
- Craft materials: Toothpicks, pipe cleaners, paper clips, metal wire, rubber bands, paper, etc. Note: Velcro tape is another option, but this might result in all seeds looking the same and being successful in the obstacle course.
For teacher:
- Printed example pictures of seed designs
- An example burr (self-made or from nature)
- Measuring tape
- Stopwatch
Background Information for Teachers
This section contains a quick review for teachers of the science and concepts covered in this lesson.Most plants have to make seeds to reproduce. But it is not just enough to make the seeds, a plant also has to ensure that its seeds find a place where they can grow and start a new plant. The process of moving, spreading or transporting seeds away from the parent plant is called seed dispersal. As plants are usually immobile, they have to engage in other strategies to make sure their seeds are spread. Dispersal of seeds is very important for the survival of plant species. If plants grow too closely together, they have to compete for light, water and nutrients from the soil. Seed dispersal allows plants to spread out from a wide area and avoid competing with one another for the same resources.
Figure 1. Some examples of seeds that are dispersed via animals, wind, and water.
Plant seeds, such as shown in Figure 1, are dispersed in several different ways. In some plants, seeds are housed within a fruit (such as apples, oranges, or berries). These fruits, including the seeds, are eaten by animals who then disperse the seeds when they defecate. Some fruits can be carried by water, such as a floating coconut. Other seeds are dispersed by the wind—such as the "winged" seeds from a maple tree that spin and "helicopter" through the air as they fall or the light feathery seeds from a dandelion that can catch on the breeze. The longer a seed stays in the air, the farther it can be blown by the wind, helping the plant species widely scatter its offspring.
Yet another clever dispersal strategy is used by plants that cover their seeds in hooks or spines as shown in Figure 2. These so-called burrs are designed in a way that they attach to an animal's fur as it passes by. Eventually, the seed will fall off and grow into a new plant. Burdock, Sea Holly, and Cocklebur are some plant species that disperse their seeds this way.
Figure 2. Examples of plant seeds that have hooks and spines.
In this lesson, students will design their own plant seed. Their seed has to be able to attach to a mockup animal (wool glove) and has to stay attached while students carry it through an obstacle course. By designing the seed, students will notice how certain structures on a plant seed are designed to serve a particular function. At the same time, students will realize that many plants are dependent on animals for seed dispersal and successful reproduction.
