Forces and Motion
Each force acts on one particular object and has both strength and a direction. An object at rest typically has multiple forces acting on it, but they add to give zero net force on the object. Forces that do not sum to zero can cause changes in the object’s speed or direction of motion. (Boundary: Qualitative and conceptual, but not quantitative addition of forces are used at this level.)
The patterns of an object’s motion in various situations can be observed and measured; when that past motion exhibits a regular pattern, future motion can be predicted from it. (Boundary: Technical terms, such as magnitude, velocity, momentum, and vector quantity, are not introduced at this level, but the concept that some quantities need both size and direction to be described is developed.)
Types of Interactions
Objects in contact exert forces on each other.
Electric and magnetic forces between a pair of objects do not require that the objects be in contact. The sizes of the forces in each situation depend on the properties of the objects and their distances apart and, for forces between two magnets, on their orientation relative to each other.
Ecosystem Dynamics, Functioning, and Resilience
When the environment changes in ways that affect a place’s physical characteristics, temperature, or availability of resources, some organisms survive and reproduce, others move to new locations, yet others move into the transformed environment, and some die.
Social Interactions and Group Behavior
Being part of a group helps some animals obtain food, defend themselves, and survive. Groups may serve different functions and vary dramatically in size.
Evidence of Common Ancestry and Diversity
Some kinds of plants and animals that once lived on Earth are no longer found anywhere.
Fossils provide evidence about the types of organisms that lived long ago and also about the nature of their environments.
Adaptation
For any particular environment, some kinds of organisms survive well, some survive less well, and some cannot survive at all.
Biodiversity and Humans
Populations live in a variety of habitats, and change in those habitats affects the organisms living there.
Growth and Development of Organisms
Reproduction is essential to the continued existence of every kind of organism. Plants and animals have unique and diverse life cycles.
Inheritance of Traits
Many characteristics of organisms are inherited from their parents.
Other characteristics result from individuals’ interactions with the environment, which can range from diet to learning.
Some characteristics result from the interactions of both inheritance and the effect of the environment.
Variation of Traits
Different organisms vary in how they look and function because they have different inherited information.
The environment also affects the traits that an organism develops.
Natural Selection
Sometimes the differences in characteristics between individuals of the same species provide advantages in surviving, finding mates, and reproducing.
Weather and Climate
Scientists record patterns of the weather across different times and areas so that they can make predictions about what kind of weather might happen next.
Climate describes a range of an area's typical weather conditions and the extent to which those conditions vary over years.
Earth’s processes continuously cycle water, contributing to weather and climate.
Natural Hazards
A variety of natural hazards result from natural processes. Humans cannot eliminate natural hazards but can take steps to reduce their impacts.
Defining and Delimiting Engineering Problems
Possible solutions to a problem are limited by available materials and resources (constraints). The success of a designed solution is determined by considering the desired features of a solution (criteria). Different proposals for solutions can be compared on the basis of how well each one meets the specified criteria for success or how well each takes the constraints into account.
Developing Possible Solutions
Research on a problem should be carried out before beginning to design a solution. Testing a solution involves investigating how well it performs under a range of likely conditions.
At whatever stage, communicating with peers about proposed solutions is an important part of the design process, and shared ideas can lead to improved designs.
Tests are often designed to identify failure points or difficulties, which suggest the elements of the design that need to be improved.
Optimizing the Design Solution
Different solutions need to be tested in order to determine which of them best solves the problem, given the criteria and the constraints.