I just finished my first week of school, like many teachers in the Midwest. I work hard to get my Honors Chemistry students in a lab setting as soon as possible. It is difficult to find a perfect lab to do on the first or second day of school. In my mind, the ideal first chemistry lab would require no prior chemistry knowledge, involve interesting chemistry, address an NGSS standard, be relatively safe, not require expensive glassware or lab tools, and reinforce positive class norms. I have found engineering labs fit the bill! I don't know if I have found the "perfect" lab, but I have found something close I want to share!

For the last few years, I have been utilizing an engineering task as my introductory lab activity. During the engineering task, students work together in teams with POGIL-like roles (manager, recorder, presenter, and reflector) to solve an engineering problem. I use POGIL (pogil.org) and cooperative groups on a regular basis in my classroom so it only makes sense I start my class this way as well. Students conduct many inquiry labs in Honors Chemistry. During the engineering task, students get comfortable making their own claims based on evidence collected from the labs they design and scientific reasoning. Engineering design is one of the NGSS standards, so I am able to meet standards on the first day of class.

When I selected my engineering task, I was looking for a relatively safe and simple task related to chemistry. My search ended with slime. Making slime has become very popular over the years. The slime recipe using glue and borax is simple and can be modified to get different results. It is relatively safe and utilizes interesting polymer chemistry I discuss later in the school year. I decided to have my students engineer a superball that would bounce the highest in the class. This was an excellent lab that promoted great teamwork and discourse. My only problem was finding a way to quickly and accurately determine a winner. The superballs bounced, but often in all different directions. It was difficult to capture the bounce in a cellphone video or with a motion sensor. This past summer I was on the hunt for a new twist to my tried and true engineering task. Fellow ChemEd X blogger, Tom Kuntzleman, suggested that I have students engineer magnetic slime instead. The idea seemed very promising so I tried it out this past week in my Honors Chemistry classes.

Figure 1: Chemical Information

Each lab group received a set of role cards that I use during labs and POGIL activities (see the end of the post for handout). I instructed them to read the cards and assign each person a role. After we briefly discussed why we use roles and what they are, I presented the engineering task (see the end of the post for a copy of the slides I used to present the lab). I told them their task for the activity was to engineer magnetic slime so that it climbs the highest when exposed to a neodymium magnet. I also told them I expected each group to report out the % Fe present in their slime. I gave them the rough recipe of slime, but did not tell them any specific amounts to use. We discussed the SDS for each chemical so they understood that they had to wear goggles and gloves during the lab. I also gave them a chemical information chart with the purpose and molecular structure of glue, borax, and iron(III) oxide so they could make informed chemical decisions and changes between trials (figure 1). On day one, students had 15 minutes and only one cup of glue and one cup of borax (with unlimited tap water) to run multiple trials and tests create a slime consistency they thought would be ideal for the challenge.  On day two, they received a cup of iron(III) oxide and a magnet. I reviewed how to use an electronic balance and the % Fe calculation. Then students separated the slime they made the day before into different batches so they could test how different ratios of iron(III) oxide responded to a magnet.  They had another 15 minutes to complete the task and we ran the class magnetic slime tournament to crown the winner.  The winning group presented their recipe and % Fe used to the class. Afterward, groups reflected on the class norms: leave no one behind, group discussion is focused on class content, and everyone works together as a team (see figure 2).

Figure 2: Reflecting on the Challenge

The Magnetic Slime Challenge Engineering Lab was a success. It was much easier to determine a winner compared to the Superball Challenge I previously did. Students were engaged and I was able to pack a lot (chemistry content, hands-on lab, standards, class norms, and lab safety) into one activity. Reflecting on this activity, I did run into a few snags I will need to iron out for next year. Some groups, despite running multiple trials, ended up creating superballs and not classic slime. Overnight the borax had more time to react and everyone's slime was "tighter' than the day before. The superball-like slime did not combine with the iron(III) oxide very well. Early on the second day, it was evident that some groups did not have a chance at winning because of this. I will need to find a way to give them a chance at winning. I could run a second bracket for the best bounce. Or, I could allow for them to use more glue, borax, and iron(III) oxide if they want to remake their slime the second day. I could also possibly have them "purchase" the chemicals they need to help motivate students to be frugal with supplies. The winning slime would not only climb the highest towards the magnet but also "cost" the least. 

What do you think? Do you have any ideas on how to make this engineering challenge even better?

I would love to hear about your first day or week activities! What do you do? Comment below!

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