Part

Duration

Lesson Summary

Materials

1

15-30 min

CS Unplugged: Events Unplugged

Students “act out” the coded events provided.

4 envelopes with printed instructions inside

2

30-45  min

Events in Scratch

Students recreate the Part 1 unplugged activity in Scratch to reinforce events concepts.

Scratch can be used online or downloaded.

If you are using online, your students will need accounts to save their project. You can create an educator account and set up class(es) for your students to join.

per student/pair

per group

per class

• Scratch downloaded or student accounts created for online access through an educator account

• Tablet/computer

• scrap of paper

• Instructions for 4 characters from Character sheet

• 4 envelopes

• Computer display

Objectives

• Learn that events are triggers to make an action happen

• Begin to think abstractly about what computers are doing with the code we put into them.

Vocabulary

• Events - triggers that make action happen in coding, like turning a light on and off

• Sequence - the order in which the code runs

• Program - a list of commands to solve a problem

Materials:

• 4 envelopes with each character’s instruction 

Introduction

CS unplugged activities are a great way to introduce a concept by helping students either get hands-on with it or see it from a different perspective. In this CS activity, you and your students will “act out” the coded events provided.

Introduce students to the concept and use of events. 

• Ask students to share what they already know about events from their everyday experiences.

• Have students explain what they think “events” mean.

• Ask students to think about how we can give instructions to computers. 

Activity

Introduce students to the activity. Tell students that the purpose of the activity is for the class to try to figure out what the code the “characters” are running and what is the trigger to make them run it. 

Ask for 4 volunteers. Have them stand up in a line front of class and give them the envelopes in order from character 1 to 4. Ask them to open their envelopes and read the instructions silently. Confirm they understand their instructions. Position character 4 so she/he can see the writing on the envelopes. 

Before you start the exercise, ask the rest of the students to watch silently and see if they can figure out the code in the envelopes. Then start tapping character 1, 2 and 3s head, in any order allowing time for each student to “run” their code.

After a few minutes, see if anyone in the class has figured out the code being broadcast to character 4. Keep going until the class figures out all the code being broadcast.

Discussion:

• What was the trigger for each event? (answer: tapping their heads)

• How come they didn’t need to use any spoken words to communicate?

• What are some examples of “events” that trigger action in the real world? (for example, school bells, traffic lights, seat belt sign on airplane)

• What are some ways you can think of using events in Scratch?  (for example, timing a conversation, starting a scene, creating, making a character do an action like move, talk, disappear, creating multiple levels, etc.)

Objectives

• Learn how to use the Broadcast event code to make a sprite do specific actions

Materials you will need:

• Access to Scratch

Activity

Introduce students to the activity. Tell students that they are going to recreate what they did in the unplugged activity in Scratch. Events in Scratch  are represented by yellow code and include: the green flag, clicking on character, bump code and broadcast. Broadcasting in Scratch helps with interactions between sprites like pacing their conversations.

Watch a video as a class (https://www.youtube.com/watch?v=TP9fF6qkB0A&feature=youtu.be)

or demo how Broadcast events are handled in Scratch

Tell students to pick 4 sprites and 1 background for a scene in Scratch. They are going to try to recreate the unplugged activity by having 3 characters broadcast messages that cause the 4th character to do specific actions. You may need to make the instructions in the envelopes from Part 1 visible to the whole classroom.

Challenge activities

If a student finishes early, check their work and if they are ready, give them one or more of the challenges:

• Help a classmate who is stuck on a bug. Helpers don’t touch other people’s devices, but instead offer suggestions for how they might go about debugging.

• Use the broadcast event to trigger a background change

• Use broadcast event to create a new level, switching out sprites that show up between level 1 and level 2