3.39 Main Idea and Best Supporting Details Worksheet

can come from several sources. Solar panels turn sunlight into electricity, so they work best where there are many sunny days. Wind turbines use moving air, so they work best in places with steady winds. Hydroelectric power uses moving water, often from rivers or dams, to spin turbines. Even though these sources are renewable, each has limits. Solar power drops at night and on very cloudy days. Wind can be calm for hours. Hydroelectric power depends on water levels and can change river habitats if dams are used. Because of these limits, some communities use more than one renewable source and may also store energy in batteries. What is the main idea of the passage?

can look empty and damaged. However, fire does not always mean the end of an ecosystem. Some plants have thick bark that protects the living part of the tree. Other plants have seeds that sprout better after heat opens their outer coat. Soon after a fire, sunlight reaches the ground more easily because many leaves are gone. New grasses and wildflowers may grow first. Insects return, then birds that eat insects. Over time, shrubs and young trees can grow, and animals that need more cover may come back. Recovery can take years, and the exact pattern depends on how hot the fire was and what plants lived there before. Which detail best supports the main idea that recovery happens in stages after a wildfire?

can look like good deals, but comparing them can be tricky. One box might cost less, but it may also contain less food. That is why shoppers sometimes compare unit price, which is the cost for one unit, like one ounce or one sheet. For example, if a 10-ounce bag costs $2.00, each ounce costs 20 cents. If a 20-ounce bag costs $3.60, each ounce costs 18 cents, so the larger bag is cheaper per ounce even though it costs more overall. Unit price helps people make fair comparisons between different sizes. Which sentence best states the main idea?