Variables in Science Experiments **Make sure your hw is out** What makes an experiment “fair”? Do Now: Time: 3 minutes Review: Using this scenario, write a scientific question: Belle notices that her blue bird feeder is more empty than her red bird feeder after a few days. (Use one of the question outlines I gave you to help you!)

Variables A variable is something that can be changed in an experiment. A constant, or control, is something that does not change in an experiment

Science experiments use… **When you finish your notes, start thinking back to the Do Now. Think about what would be the independent variable in that experiment. What are you changing?** Independent Variable: the one factor that is changed by the person doing the experiment Dependent Variable: the factor which is measured in the experiment Control: all the factors the scientist keeps the same during the experiment Constants: all factors that can NEVER change

A birdy example… Imagine you want to see what color of bird feeders your local birds preferred. Red? Blue? Green? Remind me of a good scientific question??

Our Constants and Variables Independent Variable: Dependent Variable: Constants: everything else that is kept the same, for example: – the location of the feeders – the kind of feeder used – putting the feeders out at the same time Color of bird feeder Amount of food eaten

Our Experimental Design Controls Independent Variable Dependent Variable Copy this table into your notebook!

If everything except the independent variable is held the same, we can say: The experiment is FAIR. (ONLY the independent variable can change!)

Why is it important to only change the independent variable? Think-Pair-Share Time: 1 minute Discuss with the person next to you the above question.

If you don’t… You could get unreliable results! Only one thing can be different; if more than one thing is different, then you do not really know what is causing the change in your data! Independent Variable

Is Sam’s experiment fair? YES? NO? NO! It isn’t fair since the locations of the feeders were very different!

Is Maria’s experiment fair? YES? NO? YES! It seems fair since Maria only changed the feeder color!

Is Jessie’s experiment fair? YES? NO? NO! It isn’t fair since the feeders are not out at the same time, and we know that the weather was quite different each time. Perhaps the number and kind of birds that visited during the weeks were different due to the weather. MondayTuesdayThursday

What do you think? Terry loves birds and wants to see as many as she can in her yard. She wants to know whether she is wasting money buying an expensive mixed seed, when a cheaper brand just arrived at her local store. She wonders… will the expensive seed attract more birds to her back yard? How would you advise her to find out if the expensive seed is better?

Terry’s Experimental Design Independent Variable ? Dependent Variable ? Constants ?

Terry’s Experimental Design Independent Variable Kind of seed: Expensive Cheap Dependent Variable Number of birds that visit Constants Location of feeders Type of feeder Way she measures the amount of seed eaten and the way she counts birds $

Classwork Do the first question on your worksheet. If you finish it before the time is up, move on to the next question. Be ready to share out your answers to question 1 with the class. Refer back to your definitions of variables & the examples if you need help!! You may discuss the answers with the classmates around you. Time: 3 minutes

Classwork/Homework: 7 th – Finish Simpsons variables worksheet 8 th – Finish Spongebob variables worksheet