Apostrophes, dashes, and parentheses — ACT practice questions

At the Westbridge market, a stationary bicycle powers a small grain mill. Riders pedal to grind oats and wheat into fine flour that is finely ground. The setup turns an ordinary food-processing step into a visible lesson about energy.

Market coordinator June Park adjusted the gear ratio so most adults could keep the stones moving at a steady pace. A very high ratio ground quickly but made starting difficult; a lower one felt easier but produced flour slowly. The final setting balanced comfort and output, allowing riders of different strengths to participate without racing or straining during the market’s busiest weekend demonstrations for curious nearby visitors.

The bicycle wheel never touches the mill directly. Instead, a belt links the wheel to a smaller pulley on the grinder. Because the pulley is smaller, it spins many times for each turn of the wheel. The riders¹ effort—transmitted through the belt—rotates two stone disks.

A clear guard covers the belt and pulleys while allowing visitors to watch them move. Park chose this guard after testing several designs. She wanted a material that was transparent rather than merely light-colored, since viewers needed to see the moving parts.

[1] Grain enters through a funnel above the stones. [2] Next, grooves carry kernels inward. [3] Then, the stones crush them. [4] Finally, flour falls into a bin below.

A rider can feel the work change as more grain enters, the pedals become harder to turn. Volunteers therefore add grain slowly. They also sift the flour to remove pieces that are coarse. Nevertheless, the coarser material is not wasted: it returns to the funnel for another pass.

Park measures each batchs’ mass² before and after grinding. The comparison helps visitors see that human effort changes the grain’s form without creating more matter.