1
Did you notice his new haircut?
Sign notice by bringing your index finger from your eye to your open palm, followed by the signs for his, new, and haircut. Make sure to use an inquisitive facial expression with raised eyebrows to clearly indicate that you are asking a yes-or-no question.
2
I didn't notice the time.
To express this, you will shake your head gently to indicate the negative while signing notice. After tapping your palm, point to your wrist to sign time. The negative headshake combined with the sign effectively communicates that you failed to observe the clock.
3
Please notice the warning sign.
Start by signing please, then perform the sign for notice with a clear, deliberate motion from your eye to your palm. Finish by pointing to the sign or using the sign for warning. Maintain a serious facial expression to convey the importance of paying attention.