## Discuss Scratch

MalinC
Scratcher
8 posts

### Scratch directions not consistent with trigonometry

I'm a new Scratcher and I realize that Scratch isn't mainly made for teaching mathematics, but since I'm interested in using it precisely for that, I must raise some questions about the unconventional way Scratch handles directions. When it comes to the coordinate system, Scratch uses a regular Cartesian coordinate system, as opposed to a computer based coordinate system. I guess that Cartesian coordinates are used so that children can learn about them, since that is the convention in school mathematics. So why isn't the same line of reasoning applied to directions? If the Scratch-directions would follow conventions, Scratch would be an excellent tool for introducing trigonometry.
dracae
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

MalinC wrote:

I'm a new Scratcher and I realize that Scratch isn't mainly made for teaching mathematics, but since I'm interested in using it precisely for that, I must raise some questions about the unconventional way Scratch handles directions. When it comes to the coordinate system, Scratch uses a regular Cartesian coordinate system, as opposed to a computer based coordinate system. I guess that Cartesian coordinates are used so that children can learn about them, since that is the convention in school mathematics. So why isn't the same line of reasoning applied to directions? If the Scratch-directions would follow conventions, Scratch would be an excellent tool for introducing trigonometry.
Yep, the directions and angles are all wonky and strange…

kayybee
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

Yeah, I've tried to use trig and it's really hard.

I've found that you just have to do 90-direction to get the trig angle you want.

(Note: Scratch supports any angle, allowing coterminal angles, so you don't have to find one within the range they wrote in the point in direction block.
ProdigyZeta7
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

Just subtract 90 degrees your angle from 90 degrees for your calculations.

Last edited by ProdigyZeta7 (July 2, 2013 20:03:36)

kayybee
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

ProdigyZeta7 wrote:

Just subtract 90 degrees for your calculations.
Don't forget that scratch goes clockwise but trig goes counter.
MalinC
Scratcher
8 posts

### Scratch directions not consistent with trigonometry

Yes, you must do two things, since it starts at the wrong place and moves in the wrong direction.

Considering how many students have a hard time remembering how sine/cosine are related to the y-axis/x-axis, I would hesitate to do anything with trigonometry using Scratch in education. It would have been a nice tool for introducing sine/cosine, since trigonometry appears naturally when turning things around, but as it is now, I would swap to another program before explaining the math.
dracae
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

What system is Scratch's direction based on anyways!?

MalinC
Scratcher
8 posts

### Scratch directions not consistent with trigonometry

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
dracae
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

MalinC wrote:

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
Meh…
Oooh!
Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation!

kayybee
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

dracae wrote:

MalinC wrote:

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
Meh…
Oooh!
Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation!
That would be extremely confusing for new Scratchers.
dracae
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

kayybee wrote:

dracae wrote:

MalinC wrote:

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
Meh…
Oooh!
Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation!
That would be extremely confusing for new Scratchers.
Well, the current direction system is pretty confusing too.

NoxSpooth
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

dracae wrote:

kayybee wrote:

dracae wrote:

MalinC wrote:

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
Meh…
Oooh!
Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation!
That would be extremely confusing for new Scratchers.
Well, the current direction system is pretty confusing too.
Changing the current system will affect every single project that uses it. Imagine how hard it would be to fix them all…
dracae
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

NoxSpooth wrote:

dracae wrote:

kayybee wrote:

dracae wrote:

MalinC wrote:

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
Meh…
Oooh!
Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation!
That would be extremely confusing for new Scratchers.
Well, the current direction system is pretty confusing too.
Changing the current system will affect every single project that uses it. Imagine how hard it would be to fix them all…
Yeah, I know.
I had an idea: Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation
But apparently it's too confusing?

roijac
Scratcher
100+ posts

### Scratch directions not consistent with trigonometry

dracae wrote:

NoxSpooth wrote:

dracae wrote:

kayybee wrote:

dracae wrote:

MalinC wrote:

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
Meh…
Oooh!
Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation!
That would be extremely confusing for new Scratchers.
Well, the current direction system is pretty confusing too.
Changing the current system will affect every single project that uses it. Imagine how hard it would be to fix them all…
Yeah, I know.
I had an idea: Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation
But apparently it's too confusing?
probably
you can use the term ((90 - direction) mod (360))
dracae
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

roijac wrote:

dracae wrote:

NoxSpooth wrote:

dracae wrote:

kayybee wrote:

dracae wrote:

MalinC wrote:

dracae wrote:

What system is Scratch's direction based on anyways!?

I have also wondered about that. A clock maybe. I don't know.
Meh…
Oooh!
Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation!
That would be extremely confusing for new Scratchers.
Well, the current direction system is pretty confusing too.
Changing the current system will affect every single project that uses it. Imagine how hard it would be to fix them all…
Yeah, I know.
I had an idea: Maybe there should be multiple settings for how the directions work, like how there is multiple settings for rotation
But apparently it's too confusing?
probably
you can use the term ((90 - direction) mod (360))
Meh… That's so much work.
Especially since it's a fix for a direction system that's strange anyways.

kayybee
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

roijac wrote:

probably
you can use the term ((90 - direction) mod (360))
You don't need the modulus function.
Failord
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

I made a project that doesn't use trig, but I did manage to come up with a formula for cranking correct angles out of the system. I think it's fine the way it is.

The project…

If you're trying to teach this, script a directional translator. It might be really compex, but it can be done.

Thanks for the ride, Scratch Team and community! Unfortunately, the time has come for me to move on from Scratch, so I'll no longer be using the forums. Thanks again, and farewell!
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For old time's sake, see the revolutionary Laser Battle 2.0! Also see Unstoppable Game!

And no, the evil kumquats didn't alter my signature…
MalinC
Scratcher
8 posts

### Scratch directions not consistent with trigonometry

I do not have a problem with switching between different conventions. It is not about me handling trigonometry in Scratch, but 12-year-old Scratchers.

In my opinion, Scratch would have been an excellent tool for introducing trigonometry using the unit-circle definition, if it had followed mathematical convention. As it is now, any such introduction would have to focus on how to handle the wrong starting point in Scratch (north), and the wrong direction (clockwise). And suddenly it is not that much about trigonometry but more about arithmetics - an excellent teaching/learning opportunity getting obscured by arithmetics.

Furthermore, if you are a 12-year-old Scratcher, wanting to learn trigonometry. And if you do a search on “trigonometry” in Scratch. You will see how all those that know how to handle trigonometry the Scratch-way, use sine on the x-axis and cosine on the y-axis. For those of us that know mathematics, we know that this is mathematically wrong, even if it is a clever work-around in Scratch. But for a 12-year-old Scratcher…

Last edited by MalinC (July 3, 2013 13:38:21)

kayybee
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

I'd love to switch to trig angles too, but if we do, then we break either all the projects that already use te old system, or all the projects that made the workaround for trig angles.

And if we leave those there, and use trig angles for new projects, tons of new scratchers or anyone who don't read the announcements will get confused, especially because old projects aren't consistent with the way they changed to.

Any other ideas then?
dracae
Scratcher
1000+ posts

### Scratch directions not consistent with trigonometry

kayybee wrote:

I'd love to switch to trig angles too, but if we do, then we break either all the projects that already use te old system, or all the projects that made the workaround for trig angles.

And if we leave those there, and use trig angles for new projects, tons of new scratchers or anyone who don't read the announcements will get confused, especially because old projects aren't consistent with the way they changed to.

Any other ideas then?
What are your thoughts on what I suggested?
Two options for angles, similar to the options for rotation.