Coding Concepts Activity Solutions

Sequencing

Exercise 1

The Turtle will pause twice (as there is 2 wait blocks) and it will move 80 steps in total (this is 10 + 20 + 40 + 10 from the move blocks).

Exercise 2

The Turtle will appear to not move at all. This is for two reasons. Firstly, we would have to include wait blocks to see the Turtle moving around the canvas. As there is no wait blocks, the Turtle runs through all of the move blocks in one movement. Secondly, if you add up all of the steps (100, -100, 200 and -200) you get 0. When the Turtle moves 0 steps, it doesn’t move at all.

Exercise 3

Yes, the student has explained the code correctly.

Exercise 4

The student has accidentally put 50 into one of the move blocks, so one of the sides of the triangle will not be the same length as the others. The student has also accidentally put 90 into one of the turn blocks, so the Turtle will not turn enough to complete the triangle (the degrees should add up to 360).

The corrected code would look like the stack of blocks below:

Repetition

Exercise 1

As the repeat block will repeat 4 times, so that sound will play 4 times.

Exercise 2

The student is incorrect for two reasons:

1. The Turtle will move to the left (move -10 means move 10 steps in the direction the Turtle is facing)
2. The Turtle will move 10 times in total, not 5

The Turtle will actually move towards the left 10 times.

Exercise 3

The Turtle will move to the right 6 times in total. The outer loop repeats 2 times. The inner loop repeats 3 times.

Variables

Exercise 1

The variables will be a, b, c, d, x and y

• a will be a Number value: 5
• b will be a Number value: 10
• d will be a List value, containing: 5, 10 and 2
• c will be a Number value: 15
• x will be a String value: Hello World!
• y will be a Boolean value: false

Exercise 2

The value of times will be 3. The value of times will change like this:

1. the value of times will start at 0
2. the value of times will change by positive 2, so it would now be 2
3. the value of times will change by negative 1, so it would now be 1
4. the value of times will change by postive 4, so it would now be 5
5. the value of times will change by negative 2, so it would now be 3

The note will play 3 times, as the times variable is used in the repeat block.

Exercise 3

The 1 in the change times space bar pressed block should be a -1, instead of 1. With a -1 in the change times space bar pressed block, the change times space bar pressed variable will decrease by 1 everytime you press the space bar.

Exercise 4

As the number in the change guest number by block is 2, every second guest in the guest list will be skipped. If we change the 2 in the change guest number by block to 1, every guest in the guest list will receive an email.

Functions

Exercise 1

The is Sprite moving? block is currently a Command block. To use the is Sprite moving? block in an if block, it will have to be changed to a Predicate block.

Exercise 2

The move in secs with pen down block has three inputs. The first two inputs should values that are Numbers and the last one should be a Boolean value.

User Input

Exercise 1

The Turtle will say: Hello John. The join block joins the two bits of text together into one String value.

Exercise 2

To get the program to work as the student expects they should reverse the order of the blocks. The ask and wait block is before the say block but these should be the other way around.

Exercise 3

The student has confused the x and y axes and so all of the change x and change y blocks need to be swapped around.

The correct blocks are shown in the below image:

Branching

Exercise 1

The message: Access Denied! will appear for 2 seconds. This is because the answer will be 12345, which does not equal 1234 and consequently the instructions contained in the else block will be followed. If the user had answered with: 1234, then the message: Access to Secret Documents: Granted would have appeared.

Exercise 2

• If the age of the player is 10, the You’re the right age to play this game! message will appear.
• If the age of the player is 4, the You’re too young play this game! message will appear.
• If the age of the player is 96, the You’re too old to play this game! message will appear.

To have the message: Let’s start the game! appear only when the player is the right age, the last say block will have to be placed after the say block that is third from the top, inside the second else block.

Exercise 3

Before the repeat until:

• The number variable’s value is set to 1

The first repeat until:

• The repeat until block action is followed for the first time
• The Turtle will say: Good work Sophie, as Sophie is the first name in the student names list
• The number variable’s value is increased by 1 to 2

The second repeat until:

• The condition in the repeat until block is not true (the number variable’s value is not greater than 3)
• So, the actions in the repeat until block are followed again
• The Turtle will say: Good work Tim, as Tim is the second name in the student names list
• The number variable’s value is increased by 2 to 3

The third repeat until:

• The condition in the repeat until block is not true (the number variable’s value is not greater than 3)
• So, the actions in the repeat until block are followed again
• The Turtle will say: Good work Mary, as Mary is the third name in the student names list
• The number variable’s value is increased by 3 to 4

The program ends:

• The condition in the repeat until block is true now - the number variable’s value is 4 and consequently it is greater than 3
• So, the actions inside the repeat until block are not followed again
• The Turtle will say: Program finished! and the program will end

Lists

Exercise 1

• The a list has a length of 3
• The b list has a length of 2, as it has two items (that are both Lists)
• The c list has a length of 2, as it is the same as a with the first item removed

Exercise 2

The Stage monitor for the numbers variable will look like the image below:

The numbers variable will be a List with 4 items: 1, 20, 6 and 108.

The Turtle Geometry Program

We have included pictures of what all of the blocks in the finished Turtle Geometry program will look like. After completing the Coding in Snap! Activity, the blocks in your program should look like this image.

The version of the Turtle Geometry program that is shared on the Snap! website is slightly different to the finished program. That version does not ask how many patterns you would like the Turtle to draw, it just asks how many squares you would like the Turtle to draw in one pattern. The blocks in that version of the program look like this image.

The definition of the block that you created to draw the circular pattern for a specific number of squares should look like this image.