Ideographic: A hand 扌 raised at the right time 当; 当 also provides the pronunciationRadical:

meaning for dǎng:

  • - to resist
  • - to obstruct
  • - to hinder
  • - to keep off
  • - to block (a blow)
  • - to get in the way of
  • - cover
  • - gear (e.g. in a car's transmission)

meaning for dàng:

  • - to arrange
  • - to put in order