You can never have too many conversations about the meaning of qualitative and quantitative. This lesson gives me a great opportunity to do just that in an interactive manner because the more experience the students have with identifying types of observations and data, the more natural the conversations will become. For more on teaching qualitative and quantitative, check out these lessons: Data collection: Using metric units and collecting quantitative and qualitative data and Flipping for Basic Processes (Day 1).
I begin this section of the lesson by leading a discussion of quantitative and qualitative observations. I ask for volunteers to provide the definition of qualitative observations. I want my students to tell me that qualitative observations provide information about the quality of an object and can be observed using our senses. Once we have the correct answer, I hold up various objects and ask students to provide qualitative observations about them. As the students provide examples, such as color or shape, I ask them to explain their thinking regarding why they believe their statement is a qualitative observation. The objects I hold up range from pencils and textbooks to frogs and other items found on my desk. I then ask for a volunteer to provide the definition of a quantitative observations. I am listening for the students to say that quantitative observations deal with quantities or measurements. I hold up the same items as the first time and I ask the students to provide examples of quantitative measurements that could be observed for the items. Then I ask them to provide the method they would use to find the quantitative measurement they suggested and ask them to explain their answer. By going through this brief exercise, I get my students to create a “living” definition of these terms, one that is attached is an experience and so is much more likely to hold meaning as well as “stick” in their memory.
I then assign students a randomly selected partner for this activity. This lab is very straightforward, so it lends itself well to having students select their own partners or to allowing teachers to try out different pairings of students. I have found it to be especially useful at the beginning of the year, when I am still learning the dynamics between the students.
I hand out copies of the Gummy investigation sheet. (This is an editable version of the lab that I received from a colleague and found online. I would like to provide credit to the source, so if you know where it originated, please let me know) I spend time reviewing the various activities on the sheet with the students. I use interactive modeling to review how to perform various measures. For instance, I review how to find the mass of an object by asking a student to demonstrate the process using a triple beam balance. I then ask for volunteers from the rest of the class to explain what they observed while the student was demonstrating the process. I also ask a student to model and explain the process of using water displacement to find the volume of an irregular solid.
The students work with their partner to complete the activities listed in the lab. While they work, I circulate through the room. This is my opportunity to gauge the students' ability to conduct and accurately record measurements. I record this information on a grade sheet that I carry with me.
During this activity, some of the students have difficulty with the circumference portion as they do not quite understand how to use the string and a ruler to measure. Generally, I observe the students and wait until they are able to successfully accomplish the task on their own. This requires a lot of patience on the part of the teacher, but it is important to remember that it is okay for students to have to work for the answer. Working with their partners and discussing the process, most of the students are able to correctly perform this measurement.
Some students also have difficulty making the conversion between centimeters and decimeters and centimeters and millimeters on the measurement portion. In this instance, I make a metric conversion chart available at the front of the room. I also encourage the students to write down this information in their notes, if they did not already know it.
While the students conduct these gummy worm measurement activities, they are meeting NGSS SP5 and SP6 by collecting and analyzing data and performing mathematical calculations to determine the volume of objects. Following the steps of the activity achieves CCSS RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.
To wrap up the lesson, I ask the students to share their data with the class and compare their measurements. I begin this by first asking partner sets to share their information with the other set of partners at their table. This also provides students with an opportunity to check their work and answers prior to turning in their work. I tell the students that if they have a number that is very different from that of the other group sitting at their table, they should perform the measurement again. I expect the students to have very similar answers, because they are all using the same type of gummy worms.
After a review of the measurements, the students return to the classroom where I give them a gummy worm to eat for the taste test portion of the lab. I do not allow students to eat any items while they are in the lab. Having the students eat a new gummy worm in the classroom helps to reinforce this rule. While the students finish up their worms, I ask for volunteers to explain which measurements are qualitative and which measurements are quantitative. This can be done using the sentence stem: I know that the quantitative data is …. because...