Clink, Clank times twenty-five students can create a deafening noise in combination with twenty- five low voices, so try this to quieten your classroom.  There is the obvious use of the less durable, new foam manipulatives.  Then there is the option of giving every student a sheet of felt to soften the noise of plastic or wood manipulatives.  However, if you use felt, it has a tendency to slide around too much on students desks.  Recently a fourth grade teacher shared an idea with me which I had never thought of…use the foamy-type liner (without the peel off sticky backing) that you buy to line your kitchen cabinets.  Cut each student a rectangle to use for their desk.  This type of contact paper doesn’t slide!