Sequence, Selection and Iteration - Scratch

What three building blocks are used when designing algorithms?

• Sequencing, programming, iteration

• Sequencing, selection, iteration

• Sequencing, selection, programming

What is sequencing?

• The order in which steps are carried out in an algorithm

• The order in which we think computationally

• The process of repeating a number of steps in an algorithm

Why is sequencing important?

• To ensure the algorithm is kept to a reasonable length

• To ensure the algorithm functions as intended

• To ensure the algorithm is efficient

What might happen if the sequence is wrong?

• The algorithm may be overly long

• The algorithm may be inefficient

• The algorithm may produce unexpected results

Which of the following contains a correct sequence to make a cup of tea?

• Add water to kettle, boil water, add hot water to cup

• Add hot water to cup, add water to kettle, boil water

• Boil water, add hot water to cup, add water to kettle

Which of the following contains an INCORRECT sequence when getting dressed to go out?

• Put bread in toaster, spread jam on toast, remove toast when done, spread butter on toast

• Put bread in toaster, remove toast when done, spread butter on toast, spread jam on toast

• Spread butter on toast, spread jam on toast, put bread in toaster, remove toast when done

What is selection?

• A set of steps to follow

• A path through a solution

• A decision

Why is selection important?

• Selection allows us to include more than one path through a solution

• Selection allows us to repeat steps in a solution

• Selection allows us make our solution more efficient

How many paths can be followed from a decision?

• As many as is needed

• Three

• Two

What is iteration?

• Repeating steps in an algorithm

• A decision in an algorithm

• An error in an algorithm