[Inconsistency]Turn 15 turns clockwise but that is a decrease in angle

[SimpleSi]

Just noticed as I was doing the documentation on Motion blocks

Turn 15 turns 15 degree clockwise but directions are +ve in the anticlockwise sense.

Suggest changing it so Turn 15 turns anti-clockwise for consistency

[JohnM]

Originally, GP's angles increased going clockwise, like Scratch. But this doesn't match trigonometry and physics text books, where angles usually increase counter-clockwise. Back in June, before GP was released for beta testing, we changed GP's system of directions to match math/physics textbooks.

Two behaviors might be surprising to folks, especially those coming from Scratch:

• "turn" makes the sprite turn clockwise, but decreases the value of the direction property (the current design)
• "turn" increases the value of the direction property, but makes the sprite turn counter-clockwise (proposed change)

Whichever choice we make, someone may be surprised. A possible resolution would be to change the label of the "turn" to "turn right" (and perhaps add a "turn left" block as well). Would that help?

In any case, it would be great to mention this difference in how directions are handled in your Scratch to GP guide.

[SimpleSi]

Whichever choice we make, someone may be surprised.

I think changing the direction compared to the one used by Scratch is the one that causes the greatest surprise :)

And that increasing direction turns anti-clockwise.

So having done these two major changes, I think its better to carry on and be consistent and make Turn 15, turn anti-clockwise

Or revert everything back to the Scratch "standard"

Turn right isn't "right" - it would have to be Turn clockwise - and that would be too long :)

Note:
As a maths person, I always thought Scratch got it "wrong" with its compass type direction model but after 10 years- I've accepted it and sleep well at night. :)

So I'm not adverse to the actual major changes in GP

BUT, I'm not sure how young Scratchers will take to it - to them- GP Is going to seem to be "wrong".

Obviously, as they move on at school and start doing geometry with 0 deg being right and angles increasing anti-clockwise, they get used to "new" way - so GP matches up with that

Its a bold move :)

[JohnM]

Yep, a bold move! BTW, I also think we got it wrong with Scratch, but it's more obvious now than it was when we were making that decision. At that point, everyone had been using Logo for years and there was a strong desire to be consistent with Logo.

But that history lesson is itself an argument that GP should't cling to to the past ("turn" means "turn clockwise"); we should go with "turn" means "increase the direction angle". I'll think about changing it. It might change the behavior of a few projects, but easier to make the change now, while there are relatively few users than it will be later on.

BTW, while I think students coming from Scratch will be initially surprised at GP's handling of directions compared to Scratch, I have a feeling that it won't bother them. Once they notice that it's different they'll just shrug and get on with whatever they're trying to do. At least, that's my guess. I'm curious to hear from anyone who has observed how kids transitioning from Scratch to GP have dealt with this change.

[SimpleSi]

Once they notice that it's different they'll just shrug and get on with whatever they're trying to do. At least, that's my guess.

I think you make a good point there :)