6th Grade Practice Quiz Answer Key

  1. x and y are both zero in the middle of the screen.  x=50 means it will be on the right half of the stage.  y=-120 means it will be in the bottom half of the stage.  Combined, the sprite will be in the lower right quadrant.
  2. Since x is negative, the sprite will be on the left side of the screen.  And since y is negative, the sprite will be on the lower half of the screen.  Therefore the sprite will be in the lower left quadrant.
  3. The correct answer is (c).  After each question is answered, the answer is put into a special built-in Scratch variable called “answer” in the blue “sensing” blocks. Answers to subsequent questions will replace the answer to the previous question.  To prevent the loss of this information, store it in a variable you create for this purpose.
  4. The correct answer is (c).  Boolean expressions always result in a value of either True or False when evaluated using actual values as a program runs.
  5. Variable names help you or any other person reading your code understand your intentions.  For the computer, they can be anything as long as they are used consistently.  Only humans need them to be meaningful and descriptive.
  6. A string is a sequence of letters, numbers, or symbols.  It is different from a number in that math operations will fail when applied to a string of letters.
  7. Concatenation refers to the joining together of parts into a new thing.  The latin word root “catena” means “chain”.  In Scratch, the join block implements string concatenation.
  8. It will say 15.  The variable “a number” starts with a value of 5.  The repeat loop adds 1 to the variable each time it repeats, 10 times in total (“repeat 10”).  That adds 10 to the initial value of 5, for a total of 15.
  9. It will say 13.  The repeat loop subtracts 3 from the variable’s value each time it repeats.  Since it repeats 4 times, it subtracts 12 from 25 which is 13.
  10. The “pick random” block in the repeat loop is the problem.  It will change the correct answer each time the loop repeats, making it a moving target and very difficult to guess with the hints provided.  The “pick random” should be assigned to the variable “mynumber” just once, before the repeat loop begins, and used for comparison in the repeat loop’s boolean expression.
  11. The correct answer is (d).  The sprite will say “Try Harder” because a score of 3 is not greater than 5.  The program instructions inside the Else clause will run when the Boolean expression in the If clause is False.
  12. It is impossible to answer this as the value of the variable “mynumber” is set to a random value each time the program runs.  It is not possible to determine its value at design-time, only at run-time when the program executes.
  13. The programming instructions in the if/else block “if shield = 0 then…” will never execute.  They are inside the “else” block that will only execute when the expression “shield < 10” is false, so they will only be considered for cases when the shield variable’s value is greater than or equal to 10.  They will never execute because inside the else block, the shield variable will never be 0:  it will always be 10 or greater.
  14. The repeat block will repeat forever and the program will never continue to execute the “say” block.  This is referred to as an infinite loop.  X will never be equal to 6 because it starts with a value of 0 and increases by 4 each iteration through the repeat block.  Initially it is 0, then it is 4, then 8, and so on.  It is never equal to 6.