Use a timeline to explain cause and effect between historical events

Learning goal: Use a timeline to explain cause and effect relationships between historical events, and tell the difference between events that only come in order and events that are really connected. This lesson teaches a statement from Ohio's July 2026 K–8 social studies standards, which the Ohio Department of Education and Workforce anticipates districts will begin to implement in the 2027-28 school year.

What a timeline shows. A timeline is a line that places historical events in the order they happened. Earlier events go on the left (or the top) and later events go on the right (or the bottom). A timeline answers the question "What happened first, and what happened next?" It can also show how much time passed between events when it uses a scale, such as one space for each year.

What cause and effect means. A cause is an event or condition that makes something else happen. An effect is what happens because of the cause. Historians often ask, "Why did this happen?" When they answer, they look for causes. When they ask, "What happened because of this?" they look for effects. One cause can have several effects, and one effect can have several causes.

Why a timeline helps. A cause must come before its effect. (The diagram for this lesson spaces its four events evenly to show their order; it is not drawn to a scale of years. When you draw your own timeline, use one space for each year so the long gap before the dams shows.) A timeline lets you check that rule quickly. If someone says event B caused event A, but the timeline shows B happened after A, the claim cannot be right. A timeline also lets you see a chain: one event causes a second event, and the second event causes a third. Drawing arrows between events on a timeline turns a list of dates into an explanation.

The big misconception: order is not cause. Coming first is necessary for a cause, but it is not enough. Suppose a class planted a garden on Monday and it rained on Tuesday. The planting came first, but the planting did not cause the rain. To say one event caused another, you need evidence that connects them: a record that says people acted because of the first event, or a clear explanation of how the first event led to the second. When you draw a cause-and-effect arrow on a timeline, you should be able to say what evidence supports that arrow. Events that only happen in order get no arrow.

An Ohio example: the Great Flood of 1913. In March 1913, days of very heavy rain fell across Ohio. Rivers rose over their banks and flooded many towns. Dayton, on the Great Miami River, was badly flooded, and many people lost their lives and homes. That flood is the first event on our timeline.

People in the Miami Valley decided they needed protection from future floods. In February 1914 the Ohio General Assembly passed a law, the Conservancy Act, that allowed communities to form districts to control flooding. In June 1915 the Miami Conservancy District was organized under that law. The district, with its engineers and workers, built five dry dams on the Great Miami River and its tributaries. A dry dam lets the river flow through normally but holds back water during a flood. The district built the dams, along with levees and wider river channels, between 1918 and 1922.

A fully worked model. Put the four events on a timeline: 1913 flood, 1914 law, 1915 district formed, 1922 dams completed. Now test each arrow.

Arrow 1: flood → law. The law came one year after the flood, so the order works. The evidence is that the law was written to let communities control floods, and it was passed right after the worst flood in the state's history. This is a cause-and-effect relationship.

Arrow 2: law → district. The district was formed under the 1914 law. Without the law, the district could not have been organized the way it was. This is a cause-and-effect relationship.

Arrow 3: district → dams. The district's job was to plan and build flood protection, and it built the dams. This is a cause-and-effect relationship.

Notice the chain: flood → law → district → dams. The flood is a cause of the dams, but not a direct one. It worked through the law and the district. A timeline with arrows shows this chain better than a sentence alone.

Effects can be long-lasting. The dams were built a hundred years ago, but they are still part of the Miami Valley's flood protection. An effect of an event can last much longer than the event itself.

Checking an arrow that does not belong. Suppose a student adds "1914: a new school opened in a nearby town" to the timeline and draws an arrow from the flood to the school. The school came after the flood, but nothing in our evidence says it opened because of the flood. That arrow is not supported. The student should either find evidence or remove the arrow.

How to write a cause-and-effect sentence from a timeline. Name the cause, name the effect, use a linking word such as because, so or as a result, and give the evidence. For example: "Because the 1913 flood destroyed so much in Dayton, Ohio passed the Conservancy Act in 1914 so communities could build flood protection."

Worked example 1: Checking order. A student writes, "The dams caused the flood of 1913." On the timeline, the flood is in 1913 and the dams were completed in 1922. A cause must come before its effect, and the dams were finished nine years after the flood (1922 − 1913 = 9). The claim is wrong. The correct relationship goes the other way: the flood was one cause of the dams.

Worked example 2: Order without cause. A hypothetical timeline for a school shows: 2019, the school painted its gym; 2020, the school library got new books. The painting came first. Is it the cause of the new books? Nothing in the records connects the two. They are two events in order, so the timeline gets no arrow between them. The student writes, "These events are in order, but I have no evidence that one caused the other."

Worked example 3: A chain of causes. Using the flood timeline, explain how the flood led to the dams. Step 1: the 1913 flood damaged Dayton and other towns (cause). Step 2: as a result, Ohio passed the Conservancy Act in 1914 (effect of the flood, and cause of the next step). Step 3: under that law, the Miami Conservancy District formed in 1915. Step 4: the district built five dry dams from 1918 to 1922. Answer: "The flood caused the law, the law made the district possible, and the district built the dams, so the flood was a cause of the dams through a chain of events."

Representation task: Draw the flood timeline with four events: 1913, 1914, 1915 and 1922. Use one space per year if you can. Draw an arrow between two events only when you can write the evidence for that arrow underneath it. Add one more event from a different topic that happened in the same years, and explain in a sentence why it gets no arrow.

Independent performance: Choose a local history topic with your teacher (for example, when a school, park, bridge or library in your community was built and why). Use at least two sources to make a timeline of three to five events. Then write a paragraph that explains one cause-and-effect relationship shown on your timeline.

Success criteria: (1) events are in correct time order with dates labeled; (2) at least one arrow shows a cause and its effect; (3) your paragraph names the cause, the effect and the evidence that connects them; (4) you point out at least one pair of events that are only in order, not cause and effect; (5) you name your sources.