At KS1, i think the importance in observing bricks would stem from both how they interact with their surroundings, IE introduce the concepts of mass and friction, as has been said, but also you could bring in the concept of weathering - eg...
Look at this new part of the school, look how new the bricks look, why do they look newer etc etc etc....
That of course is assuming your LEA has any money to buy pencils, let alone bricks
