Before beginning direct instruction, decide if students will work along with you, or if you will demonstrate and have students apply on their own afterward.

Remind students that a conditional in computer science is a feature of a programming language that performs different outcomes or actions depending on whether a certain condition is true or false. Simply put, a conditional is if/then logic similar to cause and effect. A conditional can also be called a conditional statement, conditional expression, or conditional construct.

Tell students, they are going to use colors to practice the use of conditionals. They will program their bot to complete different actions based on the different colors it senses.

After today's lesson, students will be able to:

-Define a conditional as it applies to computer science.

-Build a block-based code using conditionals to program their bot to complete different actions.

-Demonstrate how conditionals are used to change the actions of their bot.

To begin, students will draw a colored pathway for their bot to move along. Explain to students, the pathway will have the colors white, red, green, and blue on it. The colors can be put in any sequence or order.

Model for students how to create the colored pathway. First, use your pencil to draw the outline of your pathway. Make sure the pathway is wide enough for your bot to fit inside. Then use your red, blue, and green markers to add colored parts or sections along the pathway. The colored parts should be about half an inch wide. The correct size of the parts can be made by coloring four lines next to one another using the entire edge of the marker tip. Remember to leave parts of the pathway white.

Have students draw and color the pathway their bot will move along. Remind them to include all four colors; white, green, red, and blue. The colored parts should be the same size and can be in any order.

After the pathway has been created, students are ready to start programming. Explain to students, they will build a program for their bot to complete different actions based on the color it senses. The colors in their program are the conditions. The colors in their program can and will change.

Tell students they will begin with the first condition, the color white. When the bot senses the color white, it will move forward one step at a time. They will apply their knowledge of conditionals to program the action of the bot. Review the term, conditional, with students. A conditional or if/then statement performs different outcomes or actions depending on whether a certain condition is true or false. If the surface color is white, then the bot is going to move forward. If the surface color is not white, then it will complete a different action.

Model for students how to begin building the program. Open up OzoBlockly and click on Level 3. Then, go to Logic in the block panel. Click the "if surface color is red, do...else..." and drag it onto your workspace. Next, click on the red square inside the block and select the color white. Finally, go to Movement in the block panel. Click the "move forward 1 step medium" block and drag it into the conditional block after the word, do."

Have students use code to program the first condition, white. They will not test their program yet since it is incomplete.

Now students will complete the first conditional statement, by adding their second condition, the color green. Tell students, when their bot senses the color green, it will skate forward slowly.

Model for students how to program the second condition. Go back to Logic in the block panel. Click the "if surface color is red, do...else..." and drag it into the conditional block after the word, else. Next, click on the red square inside the block and select the color green. Then, go to Movement in the block panel. Click the "skate medium forward" block and drag it into the conditional block after the word, do. Finally, use the drop-down menu on the block to change the block to "skate slow forward." Tell students, the program is still incomplete because the statements are nested. The statements are nested because one statement is contained inside the other.

Have students use code to program the second condition, green.

Students are now ready to add their third condition, the color blue. Tell students, when their bot senses the color blue, it will spin and move forward.

Model for students how to program the third conditional. Go back to Logic in the block panel. Click the "if surface color is red, do...else..." and drag it into the conditional block after the word, else. Next, click on the red square inside the block and select the color blue. Then, go to Movement in the block panel. Click the "spin left" block and drag it into the conditional block after the word, do. Finally, click the "move forward 1 step medium" block and drag it below the "spin left" block inside the conditional block.

Have students use code to program the third condition, blue.

Onto the fourth and final condition, the color red. Tell students, when their bot senses the color red, it will light up like a disco ball and move forward.

Model for students how to program the fourth conditional. Go back to Logic in the block panel. Click the "if surface color is red, do..." block. This block does not have "else" on it. Drag it into the conditional block after the word, else. Next, go to Light Effects in the block panel. Click the "Disco" block and drag it into the conditional block after the word, do. Finally, go to Motion in the block panel. Click the "move forward 1 step medium" block and drag it below the "disco" block inside the conditional block. Tell students, all of the nested statements in your program are now complete.

Have students use code to program the fourth condition, red.

Time for students to complete the program and test it! Remind students, in order for a conditional to continuously be checked, they will need a forever loop. Otherwise, when they run the program, the bot will quickly check if it senses a certain color and nothing will happen.

Model how to add the forever loop. Go to Loops and click on a "repeat forever do" block. Drag the block above the "if surface color is white do" block to wrap the loop around the entire sequence.

Have students add a forever loop to their program. Then have them place their bot on one end of the pathway and run their program. They should watch their bot as it completes a sequence of actions based on the condition or color it senses on the pathway.

Tell students, the fun isn't over yet! The program they created uses color as a condition.

Instruct students to change the colors in the "if surface color is" blocks to program their bot to complete a different sequence of actions.

Optionally, model how to change the colors. First, click on the white square in the first "if surface color is" block and choose either red, green or blue. Then, click on the second, third, and fourth "if surface color is" blocks in order and choose a different color.

After students have changed all four colors, have them run their program again. Their bot will now complete a different sequence of actions.

Looking for more? Have students:

1. Change the colors again in their program to see a different sequence of actions.
2. Add the "say color" block from the Sounds category to program their bot to say the color it senses on the pathway aloud.
3. Use different blocks from the Movement and Light Effects categories to change the actions inside each conditional.