2E: Compound and Nested Conditionals

Make sure that your CoDrone Mini is paired before starting the lesson! If you forgot how to do this, make sure to review how to pair to Blockly here.

Review: Conditionals are statements that help programs make decisions depending on if the statement is true or false. In Blockly, conditionals include if, else if, and else statements. You actually use conditionals to make decisions in your own life!

Some examples:

• If it’s sunny, I’ll play outside.
• If my alarm goes off, I’ll wake up. Else, I’ll sleep in.

Compound conditionals are a way to test two conditions in just one statement. There are two ways to do this with one block in Blockly! You can test if both conditions in a statement are true, or you can test if just one condition is true.

To start, go to the light purple logic menu in Blockly and look for the ____ and ____ block.

The logical and will perform an action only if both conditions are true. If one is false, the entire statement will return as false and the program will move on.

To test if two conditions are true, you need to select and from the dropdown menu. 

Next, put a Boolean value, or a true/false statement, in each space. You can use blocks from a variety of the Blockly menus, but those in the logic and math menus will probably make the most sense.

Once you have the conditions you want to test, you can add them to your conditional block! Have your CoDrone Mini fly in a circle if pi is greater than 3 AND if pi is not equal to the square root of 9. Else, it should hover.

Try changing the symbols in the equation and then run the program. What happens if one of the conditions is no longer true?

The logical or will perform an action if one of the conditions is true. Even if the other one is false, the entire statement will return as true!

To test if one of the conditions is true, you need to select or from the dropdown menu. After that, you can start creating your conditions just like you did with the logical and.

Add the conditions to your condition block and then you can finish the rest of your program! Have your CoDrone Mini pitch forward and then roll to the right if the square root of 100 is equal to 10 OR if the remainder of 64 divided by 10 is equal to 10. Else it should hover.

Try changing the symbols in the equation and then run the program. What happens if both conditions are no longer true?

There may be some situations where you need to make a decision based on another situation. Sound confusing? Think about when you’re hungry:

• If I’m hungry and if it’s morning, I’ll eat breakfast. 
• Else, if I’m hungry and it’s afternoon, I’ll eat lunch. 
• Else, if I’m not hungry, I’ll drink water.

One way to do this in programming is with a nested conditional, which is an if statement inside of another if statement. These are very useful when you have multiple conditions for the same purpose (like eating when you’re hungry) or when something needs more follow-up (like figuring out what to eat based on the time of day).

Program your CoDrone Mini so if 9 x 9 is less than or equal to 100, it will move on to the next if statement. Else, it will hover for 1 second. Next, if 9 x 9 is greater than or equal to 50, it should throttle up and yaw to the right for two seconds at 50% power. Else, it will pitch forward for 1 second at 50% power. Don’t forget to have it land!

Challenge: CoDrone Calculator 2.0

Remember your CoDrone calculator from the first conditionals lesson? You’re going to expand on it with your new conditionals knowledge! Program your CoDrone to fly in different patterns based on if the mathematical equations you answer are true or false.

Rules:

• You must use at least one compound conditional with a logical and statement, one compound conditional with a logical or statement, and one nested conditional.
• Don’t forget an emergency stop!