What Are the Basic Control Structures and Design Tools Used in Designing Solutions to Programming Problems? A control structure, also known as a construct, depicts the logical order of program instructions. A sequence control structure shows one or more actions following each other in order. A selection control structure tells the program which action to take, based on a certain condition. Two types of selection control structures are the if-then-else control structure, which yields one of two possibilities (true or false), and the case control structure, which can yield one of three or more possibilities. The repetition control structure enables a program to perform one or more actions repeatedly as long as a certain condition is met. The two forms of the repetition control structure are: the do-while control structure, which tests a condition at the beginning of the loop, in a process called a pretest, and continues looping as long as a condition is true; and the do-until control structure, which tests a condition at the end of the loop, in a process called a posttest, and continues looping until the condition is true. Some design tools include a program fl owchart, or simply flowchart; pseudocode; and the UML (Unifi ed Modeling Language).