This blog post is a guest post from science teacher, Krisi Hyllen, from Lodi Middle School. Permission has been obtained to use student images in this post.
The Most Engaging Density Lab Ever
What could be more fun than dunking your students in a tank of water all in the name of science? That’s exactly what the 8th grade teachers at Lodi Middle school do each fall as the end of the first quarter arrives. It isn’t just for kicks either.
During the previous weeks leading up to the infamous Archimedes Lab my students plunder through the topic of density through a variety of activities. Some of which they consider engaging, like the online density simulator at the University of Colorado website, others not so much. Their eyes glaze over and their minds wander. They are 8th graders after all. Someday they’ll appreciate the “drudgery” I put them through.
Just when they think they will die if I say the word density one more time I ask a very important question. “How can we find YOUR density?” In the past we’ve had a blast dunking various objects into water to find the volume and density, but usually someone will blurt out, “Dunk us in water!” The introduction to the Archimedes Lab begins.
Student Density Lab Materials
- Scale that weighs in kg
- Tub
- PVC pipe and connector for runoff
- Archimedes Lab Sheet
- Hose
- 4 buckets measured in increments of 5mL up to 15mL
- Ladder
- Wooden board
- Towel
- Parent permission forms
- Archimedes Lab Sheet
- Job lanyards (optional)
Density Lab Day 1
Read the story of Archimedes and how he used displacement to determine the density, and thus the purity of King Hiero’s crown. Show pictures of Archimedes in his tub or pictures of water displacement. I’ve done this lab in the past and I'm able to have the students watch a slide show of pictures from last year’s lab to get them excited about being dunked.
Pass out permission forms to interested students. I have a first come first serve policy and students have one week to return their forms. If more than 5 students volunteer then those students will go in the tub. Be prepared for alternates, no shows, and last minute drop outs. It's best to have a couple of students on standby. You will need to determine how many volunteers you can manage for each class you teach. Each period at my school is 54 minutes and I have found that I can easily dunk 5 students in that amount of time.
Density Lab Day 2
Pass out the Archimedes Lab sheet. Students will fill out the front page including their hypothesis, the formula for density, and the names of our volunteers.
Each volunteer then gets on the scale to determine their mass in kg and we all record that information.
Assign jobs. You will need to decide which jobs will work for your students. The jobs I use include:
- Tanks Guides: the tank guides hold the wooden board across the tub that students use to help them have a steady place to sit as they get into the tub.
- Ladder: the ladder person holds the ladder as the student gets in and out of the tub.
- Faucet: this person is responsible for keeping the tub filled up to the bottom of the spout.
- Restroom Girl and Restroom Boy: these two students are responsible for monitoring the restrooms as the student volunteers change.
- Buckets #1, #2, #3, and #4: the bucket people will gather the displaced water
- Camera: there is always a student or three who wants to take pictures!
- Data Recorder: this student will record the amount of water displaced and share it with the rest of the students.
Go through all the jobs that are required to pull this lab off successfully. Explain each job and assign jobs to student volunteers.
Remind the volunteers who are going in the tub of what they need to bring: swimsuit, towel, shorts and shirt to cover swimsuit.
At the end of the day 2, set up the lab including the tub, ladder, board, 4 buckets marked with Liter lines up to 15 L, hose, and chairs for the rest of the class. (Have your last period of the day bring chairs outside as they leave). Fill the tub and cover it with a towel.
Density Lab Day 3
Sent the volunteers to the bathroom to change while the job volunteers put on their job lanyards. The job lanyards were created this year by a colleague that added a bit more fun to the event, though I’ve done this lab without them successfully. You'll have to make your own.
Everyone gets out their Archimedes lab sheets along with their notebooks (so they have a hard surface to write on), a pencil, and heads outside. While waiting for the volunteers to return from the restrooms go over each job with the job volunteers. It is important for the ladder person to hold the ladder steady. The four bucket people must carefully watch the water level and switch buckets quickly. The board people must hold the board steady and evenly on each side as the students get into the tub. The faucet person must be sure the water level is just at the bottom of the spout. The data recorder helps the bucket people calculate the total water volume, and then records and shares this information with the rest of the students who also write it down on their lab sheets.
Once the students know their jobs, they pretty much take over the lab and run it on their own only needing my guidance where I see it needed. After all the volunteers have gone in the tub and the data has been recorded, send the students off to the bathroom to change while the rest of the students head into the classroom pack up for their next class. Have the last class of the day bring the chairs back inside the classroom.
Density Lab Day 4
Go over the volume results to be sure everyone has the correct information and the students who were dunked can also get the information onto their lab sheets. I like to fill out my own Archimedes Lab sheet along with them. Using calculators the students then calculate the density of each student volunteer, rounding off to the 4th decimal digit. We finish the lab questions together discussing each question and the students look back to their hypothesis.
In the end my students discovered that density can actually be fun, they will not die of boredom, and wearing socks in the Archimedes tub is not such a good idea. May your days of teaching density be inspiring!
Kristi Hyllen
8th Grade Teacher
Lodi Middle School
