TASK DEFINITION: Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.
PROBLEM: Fact 1: when a hemisphere is tilted away from the sun , that hemisphere receives less direct sunlight. 
Fact 2: The less direct the sunlight, the colder the weather.

SOLUTION: When a hemisphere is tilted away from the sun, the weather is colder.

PROBLEM: Fact 1: mechanical weathering is when rocks are broken down by mechanical means. 
Fact 2: Ice wedging is the most important form of mechanical weathering.

SOLUTION: rocks can be broken down from ice wedging.

PROBLEM: Fact 1: a sandbar is formed by water moving sediment downstream. 
Fact 2: Numerous sandbars and abundant woody debris provide valuable habitat for aquatic species.

SOLUTION:
habitats for aquatic species are formed by water moving sediment downstream.

