Learning about the Four Preparatory Sundays of Great Lent (and activities for children)
Paidea Classics offers these products that could be helpful:

Paschal lenten calendar based on the Synaxarion of the Lenten Triodion and the Pentecostarion. It starts on Zacchaeus Sunday and goes through Great Lent, Pascha, Ascension, Pentecost and ends on the Sunday of the New Martyrs. There are 41 small windows to be opened each day of the Paschal season. They will reveal an icon for that day. It comes with a numbering guide, a book to explain each day and a mailing envelope. 11×14

The Twelve Great Feasts for Children: The Annunciation

The Twelve Great Feasts for Children: The Entry of our Lord into Jerusalem

The Three Day Pascha Series: Great and Holy Friday

The Three Day Pascha Series for Children: Great and Holy Saturday

The Three Day Pascha Series for Children: Pascha, The Feast of Feasts