Page 261 - Learn To Program With Scratch

NewGame starts by clearing the speech bubble from the previous puzzle
(if any) and initializing the clicked variable to 0 u. It then saves the number
of the randomly selected puzzle in a variable called puzzleNum v. After that,
it reads the starting position of the selected puzzle from the index list and
saves it in the pos variable w. The script then uses pos to read the answer
of that puzzle and saves it in puzzleAnswer x. Next, the script adds 1 to pos
so it points to the first puzzle instruction, and it starts a repeat until loop
to say the puzzle’s instructions in order y. After saying each instruction,
the script waits for the clicked variable to be set to 1 before moving to the
next instruction z. When the loop finds an empty element, it exits, and the
script says the puzzle’s answer {.

try it out 9-10

If you delete one of the puzzles or change the number of instructions for some
puzzles, then you would need to rebuild the index list to match up with the instr
list . Write a procedure that automatically populates the index list based on the
current contents of the instr list . The key is to search for the empty strings in the
instr list, as these indicate the end of one record and the start of the next record .

Flower Anatomy Quiz

FlowerAnatomy In this section, I’ll use a quiz on the parts of a flower to demonstrate
.sb2 how to build simple quizzes in Scratch. Figure 9-36 shows our example
application’s interface at the beginning of the quiz and after the program
checks the user’s answers. Anyone taking the quiz will enter the letters to
match the labeled parts of the flower and then click the Check button to
check the answers. The program compares the user’s answers with the cor-
rect ones and provides feedback using the green check mark and the red X
icons next to each answer.
User interface
after clicking the
Check button

Reset sprite
Check sprite Letter YesNo
sprite sprite
Figure 9-36: The user interface for the flower quiz

This quiz uses three lists. The first (named correctAns) contains the let-
ters that correspond to the right answers for the nine parts of the quiz. The

Lists 239

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