3 Give examples of ways people can improve soil quality and crop growth (e.g., irrigation, fertilizer, pest control).
4 Compare and contrast how different cultures meet needs for basic nutrients by consuming various foods.
5 Evaluate the nutritional value of different foods by analyzing package labels.
2.1 Materials can be classified as solid, liquid or gas based on their observable properties.
2.1.a Solids tend to maintain their own shapes, while liquids tend to assume the shapes of their containers, and gases fill their containers fully.
1 Materials can be classified as solid, liquid or gas. All forms of matter have weight and take up space, but each form has unique properties.
2 Solids are the only form of matter that have a definite shape. A solid's shape can be changed by hammering, twisting or stretching, but its weight remains the same. Solids can be hard, soft, bouncy, stretchy or grainy.
3 Solids take up a definite amount of space (volume); the volume does not change if the solid is placed in different containers.
4 Liquids do not have a definite shape; they flow to the bottom of a container and take on the shape of the part of the container they occupy. Liquids pour and flow from a higher point to a lower point; some liquids flow faster than others.
5 Liquids have a definite volume. When a liquid is poured into different containers, the shape of the liquid may change, but the volume does not.
6 Gases are made of particles too small to see, but they still take up space and have weight. Gases do not have a definite shape; they take on the shape of whatever container they occupy. For example, the air in an inflated balloon can be squeezed and reshaped.
7 Gases do not have a definite volume; they spread out in all directions to fill any size container, or they keep spreading in all directions if there is no container. For example, blowing even a small amount of air into a balloon immediately fills the entire balloon; the smell of baking bread eventually fills the entire house and even outside.
2.2 Plants change their forms as part of their life cycles.
2.2.a The life cycles of flowering plants include seed germination, growth, flowering, pollination and seed dispersal.
1 Flowering plants progress through a sequenced life cycle. First, seeds sprout (germinate), then seedlings grow into adult plants with leaves and flowers. If the flowers are pollinated, seeds develop that will grow into new plants to continue the life cycle.
3 Seeds contain the beginnings of a new plant (embryo) and the food (energy source) the new plant needs to grow until it is mature enough to produce its own food. Different plant varieties produce seeds of different size, color and shape.
4 Environmental conditions, such as temperature, amount of light, amount of water and type of soil, affect seed germination and plant development.
5 A plant's seed will grow into a new plant that resembles but is not identical to the parent plant or to other new plants. For example, marigold plants produce marigold seeds that grow into new marigold plants. Individual marigolds, however, vary in height, number of leaves, etc.
6 Seedlings are young plants that produce the structures that will be needed by the plant to survive in its environment: Roots and leaves begin to grow and take in nutrients, water and air; and the stem starts to grow towards sunlight.
8 Flowers have structures that produce pollen, attract pollinators and produce seeds that can grow into new plants. Some flowers have structures that develop into fruits, berries or nuts that contain the seeds that can grow into new plants.
9 Some seeds fall to the ground and germinate close to the parent plant; other seeds are carried (dispersed) by wind, animals, or water to places far away. The structure of the seed is related to the way it is dispersed.
2.3 Earth materials have varied physical properties that make them useful in different ways.
2.3.a Soils can be described by their color, texture and capacity to retain water.
1 Soil is a mixture of pieces of rock (particles), living and once living things (humus), water and air. The components of soil can be separated using sieves and settlement tests.
2 There are different types of soil that vary from place to place. Soil properties can be observed and compared. Soils can be classified by properties such as color, particle size, or amount of organic material (humus). Digging a deep hole shows that soils are often found in layers that have different colors and textures.
3 The size of the particles in soils gives the soil its texture. Soils can be classified by how they feel: Sandy soils feel gritty, silty soils feel powdery, clay soils feel sticky, and soils with small rocks feel rough and scratchy.
4 The broken rocks that make up soils can be tiny (silt and clay), medium (sand), or large (pebbles). Soils can be classified by the size of their particles.
5 A soil's texture affects how it packs together; soils that pack together tightly hold less air and water than soils that stay loosely packed.
6 There are different types of soil that vary from place to place. Some soil types are suited for supporting the weight of buildings and highways; other soil types are suited for planting food crops or forest growth.
2.3.b Soils support the growth of many kinds of plants, including those in our food supply.
1 Many plants need soil to grow. Soil holds water and nutrients that are taken in (absorbed) by plant roots.
2 Soil is a habitat for many living things. Some organisms live in the soil and others live on the soil. Worms and other underground animals create spaces for air, water and plant roots to move through soil.
3 Plants we eat ("crops") grow in different soil types. Plant height, root length, number of leaves, and number of flowers can all be affected by how much water, air and organic material the soil holds.
4 To support the growth of different plants, people can change the properties of soils by adding nutrients (fertilizing), water (irrigating) or air (tilling).
2.4 Human beings, like all other living things, have special nutritional needs for survival.
2.4.a The essential components of balanced nutrition can be obtained from plant and animal sources.
1 People need to eat a variety of foods to get the energy and nutrients they need to grow, move and stay healthy. Foods are classified as grains, fruits, vegetables, dairy, meats and beans, and oils.
2 Some foods people eat come from plants that grow wild or are planted by farmers as crops. A fruit is the ripened ovary of a flower; vegetables are the roots, stems, leaves or flowers of plants.