When Moses comes asking for his people to be allowed to go hold ‘a festival to the LORD’ in the desert, Pharaoh concludes the people have too much time on their hands to even be thinking of such things. The Israelites are being forced to build cities for Pharaoh, so he commands the foremen to stop supplying the people with the straw for making the bricks. This means they have to go out and gather the straw for themselves. Yet they will be required to produce the SAME number of bricks as before

The story is found in Exodus 5 (see esp. v. 7)

http://www.biblegateway.com/passage/?search=Ex%205&version=31

As a result of this the expression “bricks without straw” has come to refer to expecting someone to perform a task without giving them the necessary materials.

http://www.bartleby.com/81/10838.html

Note that the “bricks without straw” story follows a pattern in the book of Exodus. Much of the story of the book is about “the LORD VERSUS Pharaoh and the gods of Egypt”. The book is constantly drawing contrasts between how the two sides behave and what they are able to do. On the one hand, Pharaoh is KILLING the Hebrews, drowning their baby boys in the Nile — God responds by rescuing his people through the waters of the Red Sea, and drowning the Egyptian armies (similarly, he judges the firstborn of Egypt while sparing those of the Israelites, at Passover). The plagues story is not just about judgment, but about a “contest” between the God of the Hebrews and Pharaoh.

As for the bricks. . . Pharaoh has enslaved the people to build his cities, gives them NO rest and forces them to gather straw… much more than they can do. Later in the book, God will call the people to make a tabernacle-dwelling for HIM, but will supply them with all the materials they need (even gold and silver ‘plundered’ from the Egyptians!). He ALSO sends them out to gather every day — that is to gather the “manna” (nicknamed “bread from heaven”) for them to eat– BUT he assures that ‘even he who gathers little’ will have enough, and calls them to REST one day in seven (Exodus 16). Similarly, the story of the actual building of the tabernacle includes –BEGINS with!– the command to rest on the Sabbath (see esp. Exodus 35). In other words, the “bricks without straw” story sets up a contrast with the graciousness of God, who gives the people everything they need, including rest –and the difference between being SLAVES of Pharaoh and servants of God.