choice middle** lower middle upper middle middle** true or false true lower middle false upper middle once again we have test followed by some actions this timehoweverthe test doesn' decide whether or not to run block of code againbut rather which of two blocks of code to run once our test - python expression that evaluates to boolean -is simplymiddle** and if this evaluates to true then we change the lower boundlower middle and if it evaluates to false then we change the upper boundupper middle either wayonce one or the other has run we move on and do not return to the test