If you ask a Thai the tone of a word they are likely use their fingers to decide the tone because the tone is integral to the word.  

 

The thumb (นิ้วหัวแม่มือ) is common tone สามัญ) 

1.The index finger (นิ้วชี้) is first tone (เสียงเอก) 

2, Middle finger (นิ้วกลาง) is second tone (เสียงโท)

3. Ring finger (นิ้วนาง) is third tone (เสียงตรี) 

4. Little finger (นิ้วก้อย) is forth tone เสียงจัตวา 

 

 

Starting with the thumb then moving through the fingers you will hear บาน บ่าน บ้าน and they will announce เสียงโท 

For หวาน, remember they can only hear it maybe not know how to spell it, 

วาน หว่าน ว่าน ว๊าน หวาน and announce เสียงจัตวา 

Maybe this means of remembering tones might be useful to learners. It has been good typing practise! 

Thanks so much OP for throwing some light on this technique. I'd only ever seen it in one of my teachers - although maybe they all do it this way, but mentally, rather than physically with the fingers.

But the technique only seems practical for native speakers who inherently know the word well enough to pick it out from amongst four imposters, but not for beginners who don't know the word well enough in the first place.

Strange isn’t it?  I think that it easy to believe that adult learners know more of the language than native speakers, in my case I had forgotten much of what I was taught of English grammar and had to relearn it in order to learn Thai.    I am told that counting on the fingers is a means of making certain that the answer is correct.

As an example of what can be forgotten can be seen in spelling of ครับ,  ครัฟ showing that the adventurous writer knows his ‘endings’. ครัช showing that they don’t! คร็ showing what? I suppose a psychologist could answer that.    

PS (ปัจฉิมลิขิต).  I have just been corrected, บ and ช are adjacent on the keyboard so ครัช is a typo but such is the nature of Thai people, that ครัช becomes modern slang. 

Quite off-topic I know but the nature of Thai people would make an interesting discussion in the General forum