When Mrs. Tibble asks Arthur to babysit her twins he is worried, but can’t say no. He carries through on his promise and sure enough, the twins set about trashing their home. Arthur can’t seem to stop them. Worse, DW keeps calling to give him advice. Her advice never works, but Arthur has his own idea. His plan works, so he gets more Tibble twin sitting opportunities. To DW’s horror, Arthur puts her in her place, saying “since you know so much about babysitting you can help“.
In Marc Brown’s usual, understated manner we see Arthur rise above his own fears and move past the bad advice of others, to take command of a tough situation. This is classic success for kids, Marc Brown style.