Planning for Engagement with Big Science Ideas
Puzzling Phenomenon or Anchoring Event
Seeds can sit around for years, but when given the proper conditions, they begin to grow and turn into full-grown plants. When an avocado seed (pit) is suspended in a glass of water, it sprouts and becomes a new plant. The seed initially sends out a root, then a stem. Leaves form on the stem over time.
- How is the Avocado Pit (seed) able to change into a new plant?
- How are new plants made from existing (old) plants?
- How do the structures of organisms enable life’s functions?
- How do organisms grow and develop?
- How to organisms get what they need to grow and develop?
- How are the characteristics of one generation related to the previous generation?
- Why do individuals of the same species vary in how they look, function and behave?
Plants are living things. Plants have basic needs, including air, water, nutrients, and light. There is a diversity of forms in the plant kingdom. Plants have structures that help them live. Plants reproduce in various ways.
Gapless Explanation of Avocado Seed to Plant (Adult Level):
The avocado seed has all the parts needed to grow, AND it includes food (stored energy and nutrients) needed to grow to the point where it can begin producing its own food.
Most plants grow from seeds, which come in a variety of shapes, sizes, and textures. Within this compact package, seeds contain everything a plant needs to grow and reproduce. The outer covering of a seed is called the seed coat. Seed coats help protect the embryo from injury and also from drying out. Seed coats can be thin and soft as in beans or thick and hard as in locust or coconut seeds. Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These generally are the first parts visible when the seed germinates.
Plants are classified based upon the number of seed leaves (cotyledons) in the seed. Plants such as grasses can be monocots, containing one cotyledon. Dicots are plants that have two cotyledons.
Seeds remain dormant or inactive until conditions are right for germination. All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate. Some seeds require fire to initiate germination.
When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat. The embryo's cells start to enlarge. Then the seed coat breaks open and a root or radicle emerges first, followed by the shoot or plumule that contains the leaves and stem.
Many things can cause poor germination. Overwatering causes the plant to not have enough oxygen. Planting seeds too deeply causes them to use all of their stored energy before reaching the soil surface. Dry conditions mean the plant doesn't have enough moisture to start the germination process and keep it going.
In order for the sprouts to grow into plants, they need soil containing nutrients, water, sunlight, air (Carbon Dioxide) the right temperature, room to grow, and time.
As the plant grows and begins to make its own food from nutrients it takes from the soil, it will grow into a larger plant. The seed itself is like a survival package. It contains the food the seed needs while it is growing roots and forming into a small plant. If the avocado plant (tree) is not reset into soil, however, it won’t be able to get nutrients needed to continue to grow, and will stop growing after it “uses up” all of the food and material saved in the cotyledons.
Gapless Explanation of Avocado Seed to Plant (Elementary Level):
What you really want students to understand:
- The avocado seed is how an Avocado plant makes a new plant.
- Seeds are one way that plants make new plants.
- Plants need water and light.
- Plants acquire material for growth chiefly from air, water, and process matter and obtain energy from sunlight, which is used to maintain conditions necessary for survival.
- The seed itself needs water and light to start growing.
- Seeds have sufficient matter and energy to get the new plant started growing.
- All organisms have external parts that they use to perform daily functions.
- Young organisms are very much, but not exactly, like their parents and also resemble other organisms of the same kind.
- Plants depend on animals for pollination or to move their seeds around.
The avocado pit is a seed. When it has water and light, it begins to grow into a new plant. It is able to grow because it has material for growing and energy stored in the seed. Once the leaves come out, the new plant makes its own food from the light and soil. If the seed is not transplanted, it will use up all of the stored energy and die. Likewise, if it doesn’t get light, it will die. The avocado fruit is created when a flower is pollinated. The pollinated flower turns into the fruit – which includes the seeds, and something that helps the seeds move to a new location. In the plants they grow in class they see the entire life cycle from seed to flower and seed pod with new seeds.
Not all plants grow the same way – grasses grow differently than alfalfa, which has stems. When the leaves on the alfalfa are cut off, the plant cannot make food, and doesn’t grow new leaves, so it dies. Grasses will continue to grow, and are then able to make new food, and continue to live.
Seeds are not the only way to make new plants, though. If part of a plant stem with nodes on it have the right conditions, the stem will grow. Humans have learned to do this and many of our food crops come from planting parts of plants rather than seeds. Potatoes are an example of a stem that creates a new plant.
LS1-A Structure & Function: All organisms have external parts. Different animals use their body parts in different ways to see, hear, grasp objects, protect themselves, move from place to place, and seek, find, and take food, water, and air. Plants have different parts (roots, stems, leaves, flowers, fruits) that help them survive and grow. (1-LS1-1)
LS1-B Growth and Development of Organisms: Adult plants and animals have young. In many animals, parents and the offspring themselves engage in behaviors that help them survive. (1-LS1-2)
LS1.C: Organization for Matter and Energy Flow in Organisms: All animals need food in order to live and grow. They obtain their food from plants or from other animals. Plants need water and light to live and grow. (K-LS1-1)
LS1.D: Information Processing: Animals have body parts that capture and convey different kinds of information needed for growth and survival. Animals respond to these inputs with behaviors that help them survive. Plants also respond to some external inputs. (1-LS1-1)
LS2.A: Interdependent Relationships in Ecosystems: Plants depend on water and light to grow. (2-LS2-1)
LS3.A: Inheritance of Traits: Young animals are very much, but not exactly, like their parents. Plants also are very much, but not exactly, like their parents. (1-LS3-1)
(Examples of observations could include that leaves from the same kind of plant are the same shape but can differ in size. )
LS3.B: Variation of Traits: Individuals of the same kind of plant or animal are recognizable as similar but can also vary in many ways. (1-LS3-1)
LS4.D: Biodiversity and Humans: There are many different kinds of living things in any area, and they exist in different places on land and in water. (2-LS4-1)
Age Appropriate Science and Engineering Practices
As Stated in Standards Adapted for K–2 Asking questions (science) / Defining problems (engineering) Wondering (science) / Deciding the 'rules' (engineering) Developing and using models Drawing diagrams and building models to represent how things work. Planning and carrying out investigations Doing “exploriments” Analyzing and interpreting data Comparing and looking for patterns Using mathematical and computational thinking Counting and measuring Constructing explanations (science) / designing solutions (engineering) Describing what happened (science) / Tinkering (engineering) Engaging in argument from evidence "I think ____ because I see or know ____." Obtaining, evaluating, and communicating information Writing, drawing, or talking (acting out) about what we know, read, and understand about new discoveries (things) (ELA connections)
Plants eat dirt. Seeds are not alive. Food (fruits and vegetables) are not plants. Plants take in all nutrients from their roots. Leaves take in water. Sunlight helps plants grow by keeping them warm. Plants need things provided by people. (See full article on “Common Alternative Conceptions about Plants")