Saint Valentine is the patron saint of the lovers.
Adults send a Valentine's Day card to the person they love, they offer flowers, gifts and chocolates.
In the UK and the USA, children exhange Valentine cards at schools to their sweethearts, friends and family .
A famous poem (anonymous)
Theme : Expressing feelings and affection
Vocabuary : love, like, "you ", "sweetheart", "sweet love", "sweet honey", lover, heart, chocolate, sugar, sweets (candies -US), flowers, gifts, colours..
You can make your own valentine's Day Card
Some ideas : http://www.dltk-holidays.com/valentines/cards.htm
You can write your own poem...
Some ideas : http://www.primlangues.education.fr/php/suggestion.php?id_sug=75&type=11
Other ideas (recipes, colouring pages, cards,crafts...) : http://familyfun.go.com/valentines/