Lesson 5

Conditionals Explore

To do: November 3

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Reminder: On Friday -> Test (U3 and U4) on intro to programming - variables, strings/output, key words

To do: November 3 - Warm-up #1

Consider the following code snippet below written in pseudocode. Note that <- is the assignment operator (left arrow).

x <- 1

y <- 3

z <- 4

y <- y + 2

z <- z + y

x <- x + y + z

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What are the values assigned to variables x, y, and z?

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Warm-up #2

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What is the output after this JavaScript code snippet is run? Note that the equal sign = is the assignment operator.

var num = 5;

num = num + num;

num = num * num;

num = num + num;

console.log( num );

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Warm-up #3

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What is the output after this JavaScript code snippet is run? Note that the equal sign = is the assignment operator.

var num = 10;

num = num + num;

num = num + num;

num = num + num;

console.log( num );

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U4L04 Bubble 2: Photo Liker App Activity Guide

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Unit 4 Lesson 5 - Warm Up

Prompt: On the whiteboard

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Imagine you want to make a decision about what to wear to an event. Name two pieces of information you'd want. How would you use them in your decision?

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Unit 4 Lesson 5 - Activity

“hi”

“hi there”

“c u l8r”

Strings

Made of any characters

Inside double quotes

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22

9

548

Numbers

Made of the digits 0...9

No quotes

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Information can be stored as...

“123”

123

true

Boolean

true or false

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Information can be also be stored as a...

false

Unit 4 Lesson 5 - Activity

evaluates to

<

This is a comparison operator. It’s a clue that we need to STOP and evaluate for a Boolean value.

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Comparison operators:

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3 is less than 8.

true

3

8

Unit 4 Lesson 5 - Activity

< 8

Each side of the comparison operator must be reduced to one value before we can compare

3 + 6 < 8

9

false

Unit 4 Lesson 5 - Activity

Do This:

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Evaluate the expressions on each side of the comparison operator.

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Then evaluate the expression for a Boolean value.

3

6

-

<

4

+

1

6

12

/

>

3

-

0

3

7

-

<=

10

5

9

+

==

4

+

10

3

*

)

(

Unit 4 Lesson 5 - Activity

Do This:

​

Evaluate the expressions on each side of the comparison operator.

​

Then evaluate the expression for a Boolean value.

3

6

-

<

4

+

1

6

12

/

>

3

-

0

3

7

-

<=

10

5

9

+

==

4

+

10

3

*

)

3

5

true

(

14

14

false

false

true

Unit 4 Lesson 5 - Activity

5

Any of the values in an expression can be a variable.

​

Do This:

​

Evaluate the expression for a Boolean value.

10

Note: Any expression that can be evaluate for true or false is known as a Boolean Expression.

Unit 4 Lesson 5 - Activity

5

Any of the values in an expression can be a variable.

​

Do This:

​

Evaluate the expression for a Boolean value.

10

5

10

9

9

false

Note: Any expression that can be evaluate for true or false is known as a Boolean Expression.

Unit 4 Lesson 5 - Activity

Decision time!

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Can I go to the movies? I’m allowed to if it’s before 8 o’clock.

Do This:

• What information do I need to know?
• Draw a model of a variable to store that information. Give it a name.

Unit 4 Lesson 5 - Activity

Can I go to the movies? I’m allowed to if it’s before 8 o’clock.

time < 8

I can go to the movies! 😊

I can’t go to the movies. 😞

Unit 4 Lesson 5 - Activity

time < 8

Can I go to the movies? I’m allowed to if it’s before 8 o’clock.

I can go to the movies! 😊

I can’t go to the movies. 😞

It’s 9 o’clock. Can I go to the movies?

9

Comparison operator alert!

Stop and evaluate the Boolean expression.

Assign 9 to the variable time

Unit 4 Lesson 5 - Activity

time < 8

Can I go to the movies? I’m allowed to if it’s before 8 o’clock.

I can go to the movies! 😊

I can’t go to the movies. 😞

It’s 9 o’clock. Can I go to the movies?

9

9

false

Comparison operator alert!

Stop and evaluate the Boolean expression.

Assign 9 to the variable time

Unit 4 Lesson 5 - Activity

Unit 4 Lesson 5 - Warm Up

• In your photo liker app, when would using a conditional statement be useful?

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onEvent("downButton", "click", function( ) {

likes = likes - 1;

setText("likeCounter","Likes: " + likes);

});

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Unit 4 Lesson 5 - Warm Up

• In your photo liker app, when would using a conditional statement be useful?

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onEvent("downButton", "click", function( ) {

if(numLikes>0)

{

numLikes = numLikes - 1;

}

setText("likeCounter","Likes: " + likes);

});

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What if my decision requires several steps?

Can I adopt a cat?

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I can if I have 40 dollars or more

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AND

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I am over 14 years old

Unit 4 Lesson 5 - Activity

Can I adopt a cat?

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I can if have 40 dollars or more

AND

I am over 14 years old

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Do This:

• What information do I need to know?
• Draw a model of the variables to store that information. Give the variables names.
• With a partner, discuss how the flowchart might be set up. What will the Boolean expression(s) look like? What will be compared?

Unit 4 Lesson 5 - Activity

false

age > 14

I can adopt a cat! 😊

I can’t adopt a cat. 😞

Let’s try it out. I am 17 years old and I have $39 dollars.

Can I adopt a cat? I can if I have 40 dollars or more AND I am over 14 years old.

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age

money

money >= 40

17

39

Unit 4 Lesson 5 - Activity

false

false

age > 14

I can adopt a cat! 😊

I can’t adopt a cat. 😞

Let’s try it out. I am 17 years old and I have $39 dollars.

Can I adopt a cat? I can if I have 40 dollars AND I am over 14 years old.

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age

money

money >= 40

false

17

39

true

false

Unit 4 Lesson 5 - Activity

Logical Operators:

&& AND

|| OR

! NOT

Boolean values are a type of information, so they can also be evaluated in a Boolean expression using logical operators.

If something is true and (&&) false, it evaluates to false.

Unit 4 Lesson 5 - Activity

Logical Operators:

&& AND

|| OR

! NOT

Boolean values are a type of information, so they can also be evaluated in a Boolean expression using logical operators.

false

If something is true and (&&) false, it evaluates to false.

Unit 4 Lesson 5 - Activity

Let’s take a look at Truth Tables

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In the next few slides, Boolean values will be blue, but true will be a dark blue, and false a light blue.

true

false

Unit 4 Lesson 5 - Activity

Truth Tables - used in evaluating Boolean expressions

&& AND

true

false

&&

false

true

true

&&

true

false

true

&&

false

false

false

&&

false

true and true evaluate to:

true and false evaluate to:

false and true evaluate to:

false and false evaluate to:

Unit 4 Lesson 5 - Activity

true

false

false

false

Truth Tables - used in evaluating Boolean expressions

&& AND

true

false

&&

false

true

true

&&

true

false

true

&&

false

false

false

&&

false

true and true evaluate to:

true and false evaluate to:

false and true evaluate to:

false and false evaluate to:

Unit 4 Lesson 5 - Activity

true

false

false

false

&&

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Both must be true for the Boolean expression to evaluate as true.

|| OR

true

false

||

true

true

||

false

true

||

false

false

||

true or true evaluates to:

true or false evaluates to:

false or true evaluates to:

false or false evaluates to:

true

true

true

false

true

true

true

false

||

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Either may be true for the Boolean expression to evaluate as true.

Unit 4 Lesson 5 - Activity

The ! NOT table is easy! The results are the opposite of the Boolean value.

! NOT

true

!

false

!

not true evaluates to:

not false evaluates to:

false

true

false

true

Unit 4 Lesson 5 - Activity

The Truth Table: p and q are Boolean variables. Write in IN

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Use logical operators to combine several Boolean expressions into one expression.

Can I adopt a cat?

​

I can if I have 40 dollars or more

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AND

​

I am over 14 years old

Unit 4 Lesson 5 - Activity

false

money >= 40 && age > 14

I can adopt a cat! 😊

I can’t adopt a cat. 😞

Let’s try it out. I am 15 years old and I have $40 dollars.

Can I adopt a cat? I can if I have 40 dollars or more AND I am over 14 years old.

​

​

age

money

15

40

Truth Table

Unit 4 Lesson 5 - Activity

false

money >= 40 && age > 14

I can adopt a cat! 😊

I can’t adopt a cat. 😞

Let’s try it out. I am 15 years old and I have $40 dollars.

Can I adopt a cat? I can if I have 40 dollars AND I am over 14 years old.

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age

money

15

40

&&

true

true

true

Truth Table

Unit 4 Lesson 5 - Activity

true

Key Takeaways

• A Boolean Value is a data type that is either true or false.
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• Comparison Operators <, >, <=, >=, ==, != indicate a Boolean expression
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• Each side of the Boolean expression is simplified to a single value
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• Single values on both sides of a Boolean expression are compared and result in a Boolean value (true or false)

10

2

evaluates to

<

false

4

4

evaluates to

==

true

Unit 4 Lesson 5 - Activity

Key Takeaways

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• Boolean expressions can also include Logical Operators &&, ||, ! (AND, OR, NOT). Both sides of the logical operator are reduced to a single Boolean value

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• A truth table is used to evaluate the simplified Boolean expression to a single Boolean value

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• A decision is made with the single Boolean value

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• A flowchart illustrates the steps of making a decision with a Boolean expression

true

false

evaluates to

&&

false

true

false

evaluates to

||

true

Unit 4 Lesson 5 - Activity

Homework:

• Complete U4L05 goFormative Conditionals Explore
• Submit image of today's notes and truth table of boolean values written in your IN to Hub

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Reminder: Test (U3 and U4) on intro to programming - variables, strings/output, key words

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