Day 11: Boolean Operators

Monday, March 30th, 2026

Objectives

I can explain what the and, or, and not operators do.
I can predict whether a condition is true or false using boolean operators.
I can use boolean operators in Scratch to combine multiple conditions.

Warmup: Review — Conditionals

Last week we used if blocks to make decisions in our programs. For example, we checked if a sprite was touching a wall color.

An if block checks a single condition — something that is either true or false. But what if you need to check more than one thing at the same time?

That’s where boolean operators come in.

Operator	What it does
`and`	`true` only when both conditions are true
`or`	`true` when at least one condition is true
`not`	Flips a condition — `true` becomes `false`, `false` becomes `true`

Example

Look at this program:

when green flag clicked
set [level v] to (4)
set [power v] to (55)
if <<(power) > (50)> and <(level) > (3)>> then
cast_firebolt
end

Will cast_firebolt run?

power > 50 → 55 > 50 → true
level > 3 → 4 > 3 → true
true and true → true

Yes — both conditions are true, so the and block is true and cast_firebolt runs.

What if power was 30?

power > 50 → 30 > 50 → false
level > 3 → 4 > 3 → true
false and true → false

No — with and, both sides must be true.

Checkpoint: Warmup

I can explain what and, or, and not do.
I can predict the result of a boolean expression.

Work Session: Boolean Operators in Scratch

See Boolean Operators in Flowcharts for a visual comparison of logic with and without boolean operators.

Where to Find Boolean Operators

In Scratch, the and, or, and not blocks are green and live in the Operators category. They are shaped like pointed ovals, which means they fit inside the diamond-shaped slots of if blocks.

Part 1: `and`

The and block is true only when both conditions are true. Use it when two things must happen at the same time.

when green flag clicked
forever
if <<key [space v] pressed?> and <touching [ground v]?>> then
change y by (100)
end
end

This code only lets the player jump when they are pressing space and touching the ground. Without and, the player could jump in midair.

Part 2: `or`

The or block is true when at least one condition is true. Use it when either thing should trigger the result.

when green flag clicked
forever
if <<touching [lava v]?> or <touching [spikes v]?>> then
go to x: (-200) y: (0)
end
end

This resets the player if they touch lava or spikes. You don’t need two separate if blocks.

Part 3: `not`

The not block flips a condition. Use it when you want something to happen only when a condition is false.

when green flag clicked
forever
if <not <key [space v] pressed?>> then
change y by (-5)
end
end

This makes the player fall when they are not pressing space. We’ll use this idea later this week when we build a gravity system.

Try It

Open Scratch and build a small project that uses at least one boolean operator. Here are some ideas:

A sprite that only moves when two keys are pressed at the same time (and)
A sprite that changes color when touching one of two different sprites (or)
A sprite that falls when it is not touching the ground

Checkpoint: Work Session

I built a project that uses at least one boolean operator (and, or, or not).
I can explain why I chose that operator.

Work Session 2: Learning Check

Complete the Boolean Operators Learning Check on CTLS. You will look at Scratch programs and predict whether conditions are true or false.

Here’s some practice questions while you wait.

Checkpoint: Learning Check

I have submitted the Boolean Operators Learning Check on CTLS.

Closing

Today you learned three boolean operators that let you combine conditions:

and — both must be true
or — at least one must be true
not — flips true to false

Later this week, we’ll use these operators to build a gravity system for a platformer game. The not operator will be especially important — we’ll use it to make a sprite fall when it is not touching the ground.

Standards

MS-CS-FCP.3.2 — Develop a working vocabulary of computational thinking including Boolean, branches (if…then…else), and iteration.
MS-CS-FCP.4.5 — Implement a simple algorithm in a computer program.
MS-CS-FCP.4.9 — Develop a program that makes a decision based on data or user input.

Last updated on March 30, 2026