Events Blocks

Events blocks are used to trigger action.

What events blocks are?

Events mean one action triggers another action. Example “Start to rain” action triggers the action “take ambarella”. The action “school last bell rings” triggers the action “students go home”.

Events blocks are used to trigger action. Events blocks are essential for each project. There are 6 hat blocks and 2 stack blocks available in this category.

Events blocks can be applied to both sprite and backdrop.

How to use “when green flag clicked” block?

This is a hat block. This block allows to trigger actions when the green flag in scratch is clicked.

How to use “when () keyboard key pressed” block?

This block allows to trigger actions when the key in keyboard is pressed.

You can use any of the keyboard keys given in the drop down.

How to use “when this sprite/stage clicked” block?

This block allows to trigger actions when the selected sprite/backdrop is clicked.

How to use “when backdrop switches to () backdrop” block?

This block allows to trigger actions when the backdrop switches to another backdrop. To use this block, you must have 2 or more backdrops.

First you must write the below code to the backdrop (Select the backdrop)

After that select the sprite and write the below code.

How to use “when loudness > ()” block?

This block allows to trigger actions when the loudness is greater than specific value.

How to use “when timer > ()” block?

This block allows to trigger actions when the timer is greater than specific value.

“Timer” block available in the category “Sensing”. There is a reset block as well. You can reset the timer to 0. Check the check box of the timer and see the timer on the stage.

How to use “broadcast message” block?

This block allows to internally broadcast a message. When that broadcast is received by “When I receive message” block other actions will be triggered.

This is an internal broadcast, doesn’t show to the user. You can use this to control the screen changes or trigger another action. It’s all about timing.

How to use the Broadcast message block

How to use “broadcast message and wait” block?

This block is very similar to the Broadcast message block. But it will broad cast and wait to trigger next action. Example in the below code the “Say hello for 2 seconds” action doesn’t take place until move 10 steps happen. Its waiting to trigger the instruction Say hello.

How to use “when I receive message” block?

This block allows to trigger an action when the selected sprite receives the broadcast message.

1. Describe an event which triggers another action in nature? (Example: The event “Rain starts” triggers “Take umbrella”)

2. Do you see parallel events in nature? (Example windy and rainy same time – two events take place same time). Describe your experience.