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# Overlaps and kinds
Arcade Foundations · Collide and score
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## Today
**We are learning to** make something happen when two sprites touch, and use kinds to decide which event runs.
- I can make something happen when two sprites touch.
- I can choose a sprite's kind, and say which overlap event a touch will run.
- I can keep a score.
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## Why it matters
> Pac-Man eats a dot, Mario grabs a coin, a ghost catches you: every game is full of things touching, and each touch means something different.
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💬 Discussion
## Predict
**You steer the player onto the coin. What happens?**
- Nothing: they pass through each other
- The coin vanishes and the score goes up by 1
- The player stops at the coin, like a wall
- The player vanishes
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✅ Check
## What happened?
* The coin vanishes and a score of 1 appears at the top of the screen. The player is of kind Player and the coin of kind Food, so the Player–Food overlap event runs.
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✍️ Activity
## Run it
Open the lesson at this step and try it together.
[studio.learningwaypoints.com/tutorials/code/arcade/arcade-overlaps/?full=step-2#step-2](https://studio.learningwaypoints.com/tutorials/code/arcade/arcade-overlaps/?full=step-2#step-2)
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💬 Discussion
## Investigate
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✅ Check
## Who touches whom?
**Match what touches with what happens in this game.**
| | |
|---|---|
| `the player touches the coin (Food)` | A. nothing: no event names Food and Enemy |
| `the player touches the spike (Enemy)` | B. the score goes down 1 and the spike is destroyed |
| `the coin and the spike touch` | C. the score goes up 1 and the coin vanishes |
* Answer: the player touches the coin (Food) → C. the score goes up 1 and the coin vanishes; the player touches the spike (Enemy) → B. the score goes down 1 and the spike is destroyed; the coin and the spike touch → A. nothing: no event names Food and Enemy
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✅ Check
## Which sprite?
**In the Player–Food event, which sprite is otherSprite?**
- The coin it touched
- Every Food sprite in the game
- The player
- The spike
* Answer: The coin it touched
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✅ Check
## Ava's star
Ava's overlap event is the same as this game's. She made her star like this:
**Ava added a star to her game and steers onto it. Nothing happens: no score, the star stays. Why?**
- Stars cannot be destroyed
- The star was made of kind Player, so no Player–Food event runs
- The overlap event needs to be inside on start
- The score only counts coins
* Answer: The star was made of kind Player, so no Player–Food event runs
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✍️ Activity
## Name tags (4 min)
Students wear kind cards (Player, Food, Enemy). The teacher reads an event ("Player meets Food: cheer"). Pairs that meet act only if their cards match the event.
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✍️ Activity
## Modify
- **Worth more:** Make each coin worth **5** points.
- **A second coin:** Add a second coin, of kind **Food**, somewhere else on the screen. Does it need its own overlap event?
[Open this step](https://studio.learningwaypoints.com/tutorials/code/arcade/arcade-overlaps/?full=step-4#step-4)
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💬 Discussion
## Investigate: Mix it up
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✅ Check
## Mix it up
**The ship has move with buttons with speeds 100 and 0. Which arrow keys move it?**
- Left and right only
- All four
- Up and down only
- None
* Answer: Left and right only
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✍️ Activity
## Make
Make a **collector** game:
- **good food** (an apple, a gem): touching it scores **1**, and it vanishes
- a **bad item** of kind **Enemy** (a worm, a bomb): touching it takes **1** away, and it is destroyed
Check every create block: is its kind right?
[Open this step](https://studio.learningwaypoints.com/tutorials/code/arcade/arcade-overlaps/?full=step-6#step-6)
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✍️ Activity
## Change a fruit stall game
Bananas fall into a basket at a market stall. Make them fall faster, then add a rotten tomato of kind **Enemy** that falls too and takes 2 points when caught.
[Open this step](https://studio.learningwaypoints.com/tutorials/code/arcade/arcade-overlaps/?full=step-7#step-7)
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✍️ Activity
## Kinds first (3 min)
Swap collectors with the next pair. Read out each sprite's kind before you play.
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✅ Check
## Exit ticket
**A coin is made of kind Player. The game has a Player–Food overlap event. Will touching the coin score? Why?**
* No. The event only runs when a Player touches a Food sprite. The coin is a Player, so no event runs. Change its kind to Food.