Tony Mantoan from Benedictus Deus shared a great idea for helping to explain Pentecost to kids over at CatholicDaily.org:
Cut twelve doves out of construction paper. On each dove write one of the twelve fruits of the Holy Spirit. Alternatively, you could do the seven gifts of the Holy Spirit. Hide the twelve doves around the house or yard and have a dove hunt. After all the doves are found discuss the twelve fruits with your children, or if they have already learned about them ask them to explain the ones they found. Hopefully this activity will remind them of Easter egg hunts and help them draw the connection between Easter and Pentecost.
For those of us in need of a refresher on the 12 fruits of the Holy Spirit (guilty as charged), they are: Charity, Joy, Peace, Patience, Kindness, Goodness, Generosity, Gentleness, Faithfulness, Modesty, Self-control, Chastity. The 7 gifts of the Holy Spirit are: Wisdom, Understanding, Counsel, Fortitude, Knowledge, Piety and Fear of the Lord.
Come, Holy Spirit, Creator blest, and in our souls take up Thy rest; come with Thy grace and heavenly aid to fill the hearts which Thou hast made.
O comforter, to Thee we cry, O heavenly gift of God Most High, O fount of life and fire of love, and sweet anointing from above.
Thou in Thy sevenfold gifts are known; Thou, finger of God's hand we own; Thou, promise of the Father, Thou Who dost the tongue with power imbue.
Kindle our sense from above, and make our hearts o'erflow with love; with patience firm and virtue high the weakness of our flesh supply.
Far from us drive the foe we dread, and grant us Thy peace instead; so shall we not, with Thee for guide, turn from the path of life aside.
Oh, may Thy grace on us bestow the Father and the Son to know; and Thee, through endless times confessed, of both the eternal Spirit blest.
Now to the Father and the Son, Who rose from death, be glory given, with Thou, O Holy Comforter, henceforth by all in earth and heaven.