Search the California Content Standards

Standard:
Justify the selection of specific control structures by identifying tradeoffs associated with implementation, readability, and performance.

Descriptive Statement:
The selection of control structures in a given programming language impacts readability and performance. Readability refers to how clear the program is to other programmers and can be improved through documentation. Control structures at this level may include, for example, conditional statements, loops, event handlers, and recursion. Students justify control structure selection and tradeoffs in the process of creating their own computational artifacts. The discussion of performance is limited to a theoretical understanding of execution time and storage requirements; a quantitative analysis is not expected. For example, students could compare the readability and program performance of iterative and recursive implementations of procedures that calculate the Fibonacci sequence. Alternatively, students could compare the readability and performance tradeoffs of multiple if statements versus a nested if statement.

Standard:
Iteratively design and develop computational artifacts for practical intent, personal expression, or to address a societal issue by using events to initiate instructions.

Descriptive Statement:
In this context, relevant computational artifacts can include programs, mobile apps, or web apps. Events can be user-initiated, such as a button press, or system-initiated, such as a timer firing. For example, students might create a tool for drawing on a canvas by first implementing a button to set the color of the pen. Alternatively, students might create a game where many events control instructions executed (e.g., when a score climbs above a threshold, a congratulatory sound is played; when a user clicks on an object, the object is loaded into a basket; when a user clicks on an arrow key, the player object is moved around the screen).

Standard:
Compare levels of abstraction and interactions between application software, system software, and hardware.

Descriptive Statement:
At its most basic level, a computer is composed of physical hardware on which software runs. Multiple layers of software are built upon various layers of hardware. Layers manage interactions and complexity in the computing system. System software manages a computing device's resources so that software can interact with hardware. Application software communicates with the user and the system software to accomplish its purpose. Students compare and describe how application software, system software, and hardware interact. For example, students could compare how various levels of hardware and software interact when a picture is to be taken on a smartphone. Systems software provides low-level commands to operate the camera hardware, but the application software interacts with system software at a higher level by requesting a common image file format (e.g., .png) that the system software provides.

Standard:
Compare and contrast cryptographic techniques to model the secure transmission of information.

Descriptive Statement:
Cryptography is a technique for transforming information on a computer in such a way that it becomes unreadable by anyone except authorized parties. Cryptography is useful for supporting secure communication of data across networks. Examples of cryptographic methods include hashing, symmetric encryption/decryption (private key), and assymmetric encryption/decryption (public key/private key). Students use software to encode and decode messages using cryptographic methods. Students compare the costs and benefits of using various cryptographic methods. At this level, students are not expected to perform the mathematical calculations associated with encryption and decryption. For example, students could compare and contrast multiple examples of symmetric cryptographic techiques. Alternatively, students could compare and contrast symmetric and asymmetric cryptographic techniques in which they apply for a given scenario.

Standard:
Demonstrate the flow of execution of a recursive algorithm.

Descriptive Statement:
Recursion is a powerful problem-solving approach where the problem solution is built on solutions of smaller instances of the same problem. A base case, which returns a result without referencing itself, must be defined, otherwise infinite recursion will occur. Students represent a sequence of calls to a recursive algorithm and show how the process resolves to a solution. For example, students could draw a diagram to illustrate flow of execution by keeping track of parameter and returned values for each recursive call. Alternatively, students could create a video showing the passing of arguments as the recursive algorithm runs.

Standard:
Develop solutions to security threats.

Descriptive Statement:
Designing and implementing cybersecurity measures requires knowledge of software, hardware, and human components and understanding tradeoffs. Students design solutions to security threats and compare tradeoffs of easier access and use against the costs of losing information and disrupting services. For example, students could refine a technology that allows users to use blank or weak passwords. Alternatively, students could implement a firewall or proxy protection between an organization's private local area network (LAN) and the public Internet. Additionally, students could find and close exploitable threats on an infected computer in order to protect information.

Standard:
Analyze cryptographic techniques to model the secure transmission of information.

Descriptive Statement:
Cryptography is essential to many models of cybersecurity. Open standards help to ensure cryptographic security. Certificate Authorities (CAs) issue digital certificates that validate the ownership of encrypted keys used in secured communications across the Internet. Students encode and decode messages using encryption and decryption methods, and they should understand the different levels of complexity to hide or secure information. For example, students could analyze the relative designs of private key vs. public key encryption techniques and apply the best choice for a particular scenario. Alternatively, students could analyze the design of the Diffie-Helman algorithm to RSA (Rivest–Shamir–Adleman) and apply the best choice for a particular scenario. They could provide a cost-benefit analysis of runtime and ease of cracking for various encryption techniques which are commonly used to secure transmission of data over the Internet.