Teaching cause and effect can be complex. Using a medium children understand such as money or cost is a good way to show the relationship. Using something like a cell phone bill or texting bill is a quick way to showcase cause and effect, as well as the types of variables. The independent variable is how many texts you send in a month. The dependent variable is how much the bill is. Do this by having children guess how many texts they have sent in the past week. Tell them the charge per text and have them figure out the total. This showcases the way one variable is affected by the other.
Science experiments showcase variable independence as well. Line up five plants. Determine the amount of water that will be given to each plant on a daily basis. Give the first plant no water, the second plant ¼ cup per day, the third one ½ cup of water per day, the fourth plant ¾ cup per day and the fifth plant a whole cup of water per day. Decide on a time frame for the experiment and measure the plants every day. The height of each plant is the dependent variable and the independent variable is the amount of water given to each plant because that is not changed by anything other than you. You can take this a step further by quizzing the students about other independent variables that might affect plant growth.
Association worksheets are often used to teach students about variable dependency. Setting up a table stating either the dependent or independent variable and having the students decide what the corresponding variable might be helps them think through the process. You can add a bit of fun to this activity by making it a "Jeopardy" or "Family Feud" type game. Divide the class into groups and describe a situation such as: "You studied for five hours and your test score was 92 percent, whereas Bill studied for two hours and scored 81 percent. Name the dependent variable." Have the groups compete against each other to come up with the answer the fastest. Give each student a chance to earn points for his team. To ensure he understands the subject, have him offer an explanation as to why his answer is the independent or dependent variable.
Outside games can be an entertaining way to demonstrate cause and effect. Doing things like throwing eggs against the side of a building give a clear picture to the cause (throwing) and the effect (splatting) of the egg. Have the students throw the eggs at different velocities to create a greater mess. As the students giggle while throwing eggs, discuss how the throwing and the splatting represent independent and dependent variables. Measure the diameter of the broken egg splatter and award a prize to the person who causes the biggest mess.