Experiment: Does the Heads or Tails Side of a Quarter Hold More Drops of Water?
Lesson 7 of 16
Objective: SWBAT follow the steps of the scientific method to test whether the heads or tails side of a quarter will hold the most drops of water.
The Why Behind Teaching This:
Over the past week, students have been building their foundation of science tools and procedures and skills that scientists use. Now it is time for the students to put what they have learned to practice by becoming the scientists. They will follow the steps of the scientific method to test whether the heads or tails side of a quarter will hold the most drops of water. This activity is linked to standard 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.
I chose this experiment as the first to have my students conduct because I like to begin with an experiment they can do independently. This is a fairly easy experiment that even the ESE and ELL students can complete independently. The majority of the experiments done throughout the year are done in cooperative groups. I like to begin with an opportunity for each student to work through the steps alone first, without having to take others opinions into account. I also require students to repeat experiments three time to ensure valid results. In this experiment, each student applies drops of water differently which is a variable that must be controlled. The same student has to add the drops, which would mean the other group members would not get the opportunity to use the dropper, which students enjoy.
The goal of today’s lesson is for students to follow the steps of the scientific method, to test a whether the heads or tails side of a quarter hold the most drops of water. I will be reviewing some of the science tools and we will be identifying the variables in the experiment as well. I will follow up this lesson with a lesson on graphing so students can share their results with the class.
Students will demonstrate success on this activity by following the steps of the scientific method we outline together to conduct the experiment accurately. They will need to control all variables except the independent variable in order to accurate results. Students will also need to collect and record accurate data. I will be assessing all of this through obseravtion during the experiment.
Students will also be assessed through the explanations they write on the model they are required to draw during the wrap up section. They are asked to draw a model of the experiment, label each part, and write an explanation of what is happening. This will provide me with information as to whether they understand the procedures they just completed.
- A quarter
- A hand lens for each student
- Foldable, trifold, made from copy paper for each student
- Print out of the procedure for quarter experiment for each student
- Dropper for each student
- Cup of water for each pair of students
- Paper towel for each student
Making Observations Before Experimenting:
I begin the lesson today by having students take out their science notebooks and title the page Experiment: Does the heads or tails side of a quarter hold more drops of water? I have my notebook displayed on the overhead with the title written already for students to refer to as a reference. This helps the ESE and ELL students who may struggle with spelling and writing quickly. As students record the title of the lesson, I pass out a quarter and a hand lens to each student and ask them not to pick them up until I give them directions.
I draw a T-chart in my science notebook with one side titled Heads, and the other side titled Tails. Students know that anything I write in my notebook they should copy into theirs so they are already copying this as I begin to discuss the T-chart. I explain that a T-chart is used to compare two things, in this case the heads side of a quarter versus the tails side. I ask students why they think they have a hand lens to use as a tool for this activity. They explain that they will be using it to help them observe the quarter (this is review from a previous lesson). I ask them why we are not using a different tool for observing, such as a microscope. This helps me note a clear understanding of the difference between the two tools, as well as identify and correct any misconceptions.
After our discussion, I ask students to make observations about their quarter and write characteristics of both sides in their T-chart. I tell them that they can discuss these differences in their groups as they observe. I give them about 3 minutes to make and record their observations. I circulate to observe and ask questions. We discuss some of the answers the students came up with and I record some of the examples in my notebook.
Observations Lead to Experiments:
I explain to students that observations are what often lead to the first step of the scientific method. I ask them what that step is and they are able to tell me, it is the questions or purpose. I explain to them that several years ago I used to have students test how many drops of water a penny, a nickel, a dime, and a quarter could hold. Then one of my previous students observed some of the same differences they just filled in their T-chart with, and asked me if it mattered which side of the coins he used. I told him to test it out and find out. By him making those observations, it has led me to change the activity into an experiment to test his question.
I provide each student with a piece of copy paper that has the sides folded in like a trifold display board (the same set up we used for the previous scientific method foldables). I place my example under the overhead and we all write Question in the upper left hand corner as the section heading. I write Does the heads or tails side of a quarter hold more drops of water? Again, the modeling is important for my students because I have both ESE and ELL students which need that visual reference for copying. As we complete more experiments together, groups will be responsible for completing all of this together without my assistance.
I then ask students what the next step of the scientific method is and they are able to tell me the hypothesis follows the question. We all record Hypothesis as the heading for this section. I ask them how making observations of the quarter first, will help them with their hypothesis. I am looking for answers such as “It helped me see the differences”, and “It helped me see characteristics that may allow more water to build up on that side”. I ask students for examples of what the hypothesis may be. We have already discussed that in 5th grade we write our hypothesis as a cause and effect sentence so I am looking for examples of that. There are really three possible options: If I place drops of water on the heads side and tails side of a quarter, then I predict/hypothesize/believe, that the __________(heads or tails) side of the quarter will hold more drops. Or they might choose to end that statement with both sides will hold the same number of drops. Students choose which hypothesis they believe is correct and they record it on their foldable. I leave mine blank as I do not want to influence students to choose what I have written.
I remind students that the next step is to plan a way to test our hypothesis to find out if we are correct. I ask what two things our plan will consist of and they are able to tell me, materials and procedure. We write Materials as the heading in the lower left hand corner of the foldable, and Procedure as the heading in the upper right hand corner. To save time, I have the procedure for quarter experiment typed, printed, and cut out for each student. I pass one out to each student and ask them to glue it in under that section. I do this for the first few experiments because some have several steps and it takes a lot of my students a long time to write, plus they get tired of writing. I am assessing their ability to follow the steps, not their ability to copy information. As they glue in the procedure, I read the steps out loud while they follow along. We then move over to the materials section. After hearing the procedure, they are able to tell me all of the materials we will be using: a dropper, one quarter, a cup, water, paper towel.
After we have our plan written out, I ask students what the next step is, and they are excited to tell me they get to conduct the experiment now. I ask them what they should be doing while they conduct the experiment and they know they should be recording data in a chart. We move to the center section of the foldable and draw a data chart together.
Before students begin, we discuss the variables in the experiment. We record this information in their notebooks under the T-chart. We begin with the independent variable which they tell me is the side of the quarter (the one thing they are changing). Next, I ask what the dependent variable will be and they tell me the number of drops the side holds (data they are collecting). Finally, we try to name at least four control variables which students usually have a more difficult time coming up with. They tell me: the person adding the drops, the quarter being used, the dropper, the height the dropper is held from, the surface the quarter sits on, and no bumping or shaking the desks. They were able to tell me six variables to control which I thought was great.
Conducting the Experiment:
After we identify the variables, I ask a student to explain again what the steps of the experiment are. I like to do this right before they begin so the directions are fresh in their mind. I call on a student that I know often times needs directions repeated, and ask him to repeat the steps again. This allows students to hear the directions for a third time, and I can make sure he is clear on the expectations. I pass out a cup of water with two droppers in it to each pair of students and choose a student to pass out a paper towel to each student. I tell them to set the quarter on the paper towel so when the water overflows it does not make a mess and tell them they may begin testing. I circulate to observe and to remind students to count quietly as this is distracting to those around them. I also remind them to include the unit of measure, in this case, drops.
I am watching as students conduct the experiment to make sure they are collecting data accurately, and to make sure they are testing the heads then the tails, then moving on to trial two and doing the heads and tails again. I find that many students try to do all three trials on the heads side, then move on to the tails side. If they do this, and time runs out, they will not have completed trials they may only have the heads side done and not any on the tails side. Students should always do the experiment once, then move on to completed trial two all the way through, and then completed trial three.
As students are working, I go ahead and label the rest of my headings in my foldable. I write Conclusion in the bottom right section of the foldable and Graph in the bottom center section. As students begin finishing up their experiment, I collect their materials, and ask them to analyze their data and write their conclusion on their foldable. As I collect materials, I review the conclusions being written in foldables. I am checking what they have written for their conclusion to see that they restated their hypothesis and told whether it was accepted or denied by the data collected. Often times they will just write, "my hypothesis was/was not correct" and not explain it. They have to include an explanation indicating they analyzed their data.
When all students are finished, and I have collected all materials, I call on a couple of students I saw had their conclusion written correctly. The conclusion should have the hypothesis restated, whether the hypothesis was correct or incorrect, and what evidence they collected to support that. I try to find at least one student whose hypothesis was correct, and one whose hypothesis was incorrect. As students read their conclusion, I point these things out and give positive reinforcement. I ask students to rewrite their conclusion if they did not include all of these details and glue them into their science notebook with glue on the back of the center section only, not on the flaps.
Identifying Factors that Affected the Outcome:
The results of the class were about 70% tails and 30% heads. We discuss what factors may have affected some student outcomes. The students give me suggestions such as, the drops they added were larger, someone bumped the table causing it to spill over quickly, not all tails side of the quarters are the same, some students held their droppers closer or father away, etc. Some of the items mentioned were variables that we identified before beginning the experiment we I mention again how important it is to keep all those variables constant when testing because they may cause the outcome to be different. We also use this time to discuss why it is so important to repeat experiments several times, and not just do it once.
On the ouside of the foldable (flaps closed) I ask students to draw a model of the experiment, label the drawing, and explain what is happening at each part. I ask them to do this on their foldable, in their science notebooks, so they can refer to it as a reference instead of being handed into me. The exit activity reviews what we have learned about models, while also pulling in other science skills such as diagraming and labeling, and connects writing to the activity as well. They can then open the foldable to see details about each step and to see the data that was collected. If students do not finish this in the time given, they will take it home to finish as homework and I will check it in the morning the following day.