Introduction

This is the 2nd lesson in a 3 part series. In the previous lesson, students learned how to use a variable to count all the cookies in the cookie jar. In today’s lesson, we will learn how to code a conditional statement into your program to enable Ozobot to perform actions while counting.

1. On a piece of notebook paper, have students write the sentence, “If the cookieCount equals , then Ozobot will .”
2. Students will fill in both blanks with the total number of cookies in their cookie jar. This sentence is explaining what Ozobot will do when it has counted all of the cookies. For example, “If the cookieCount equals 10, then Ozobot will spin and play a happy sound.”
3. Explain to students that they have just created a conditional statement. A conditional statement tells your Ozobot to execute an action depending on whether a condition is true or false.
4. Next, have students write, “If the cookieCount equals _, then Ozobot will flash colored lights.” This will signal what Ozobot is going to do when it has counted half of the cookies. Students will fill in the blank space with half the total number of cookies in their jar.

Time to Code

We want Ozobot to flash colored lights once it has counted half of the cookies and celebrate once it has counted all of them!

1. Help students to open their program from the previous lesson.
2. Then ask students to code a celebration to celebrate counting all of the cookies.
3. Many students might create a program by adding celebration blocks after the Count With loop block, such as this (https://ozo.bot/b/7kgqvo ). While this is one way to add a final celebration move, we also want Ozobot to flash colored lights when it has counted half of the cookies.
4. Today we are going to introduce a conditional statement to enable Ozobot to execute an action depending on the condition. This means we can tell Ozobot what to do when it has counted half of the cookies and what to do when it has counted all of the cookies.

If-do Block

Let’s create a condition that enables Ozobot to flash colored lights when it has counted half of the cookies:

1. Under level 4 in the Logic category, you will find the If-do block, which represents the simplest conditional statement. When the condition you specify as an input is met, the program executes the code you place in the If statement's body.
2. Explain to students that this block is the same as the “if, then” sentences they wrote at the beginning of the lesson. We are swapping the words then with do.
3. Place the If-do block after the Wait 1 Second block.

We want to specify that Ozobot will flash colored lights when it has counted half of the blocks. To do this, we need to use the Compare block in the logic category and add it to the If statement’s body.

1. Next, copy and paste the Variable block titled “cookieCount” from the program. Add it to the first space in the Compare block.
2. In the second space of the Compare block, add a Number block and add the value of half of your cookies.
3. You have created a condition, “If the cookieCount is half the total number of cookies…”

Now that we have set the condition, we need to tell Ozobot what to do if it is met.

1. In the do statement’s body, add the Set Light Color block from level 3 and choose any colors to turn on Ozobot’s front lights.
2. Then add a Wait 3 Seconds block and a Turn Front Lights Off block. These will enable the lights to stay on for 3 seconds then turn off.
3. Ask students to look over the conditional statement they’ve created and read it as a full sentence. An example of your conditional statement should read, “If the cookie count equals 5, then Ozobot will flash green and yellow lights.”
4. Run your program. Ozobot should count all the cookies in the cookie jar and flash colored lights when it has counted half of the cookies.

Else-if do Block

Now let’s create a condition that enables Ozobot to celebrate when it has counted all of the cookies:

1. The If-do block is reconfigurable, which provides possibilities for more complex logic. You can control the program flow depending on specific outcome scenarios for the condition you are evaluating. This means we can add another condition to our statement.
2. If you press on the small gear button inside of the If-do block's upper left corner, a popup will show up. Drag the Else If block over to the white side of the pop up.
3. Copy and paste the Compare block you have created above and add it to the if statement’s body. You will need to change the value to your total number of cookies. Ozobot Blockly Share code: https://ozo.bot/b/7jkree
4. Now you have created a condition for Ozobot to execute an action when it has counted all of the cookies. Add any celebration blocks to the do statement’s body.
5. Run your program. Ozobot should count all the cookies in the cookie jar, flash colored lights when it has counted half of the cookies, and celebrate when it has counted all of the cookies. Ozobot Blockly Share code: https://ozo.bot/b/g4bqd8

Save Program

Before wrapping up, show students how to save their programs in Ozobot Blockly or by copying down their unique share code.