The search of the chametz, "bedikat chametz"
The day before the 14th of Nissan, at nightfall, we have to search for the chametz in the light of a candle. Before beginning this search, it is customary to place in various places of the house, 10 small pieces of chametz wrapped in the aluminium not to scatter new breadcrumbs in the house.
Then we recite the following blessing:
Baruch Ata Ado-Naï Elo-Hénou Melech Haôlam Asher Kideshanu Bemitsvotav Vetsivanu Al Biur chametz
בָּרוּךְ אַתָּה יְהוָה אֱלֹהינוּ מֶלֶךְ הָעוֹלָם אֲשֶׁר קִדְּשָׁנוּ בְּמִצְוֹתָיו וְצִוָּנוּ עַל בִּיעוּר חָמֵץ
Source of blessing you are Hashem, King of the universe, who sanctified us by His Commands and ordered us the burning of the chametz.