DIY Surface Bacteria Sampling Dish | Vegan

If you follow me on Instagram (#mhsfcs, #washurhands) you may be wondering why we are decorating for Christmas so early. See all of the beautiful reds and greens?

Although we would love a break from this hot muggy weather, Christmas is a long time away. Those colors you see are all kinds of microorganisms growing on surfaces in our school.

I read a lot online about testing surface bacteria with agar dishes and tape and knew the experiment would be perfect for my students to demonstrate the importance of hygiene in food preparation. I quickly found it to be cost-prohibitive. After looking through several recipes online I came up with this concoction. Because it is so quick, cheap, and easy to make, we were able to collect samples from 54 surfaces in our school!

To make four dishes, dissolve 1 tsp guar gum and 2 tsp sugar in 1/2 C hot water. Whisk vigorously with a fork because the guar sets quickly. Carefully pour the mixture into four 7" heavy duty plates.* Allow to set and place in quart-sized zipper-seal plastic bags.

*Although it sets up well, the guar gum is still a bit runny. In the future I think I will cut clear Solo cups for trays. This would also allow for the use of a microscope. They would also fit in a snack or sandwich bag which are less expensive than quart-sized.

Like most good ideas, this one came late at night. All of the recipes called for gelatin which I do not use in my home. Guar gum is a great substitute that I have on hand. It is six times stronger and at least that more cheaper than gelatin. A little goes a long way.

To test a surface, students tore 1 square of very cheap 2-ply toilet paper and wiped the whole surface.  They placed the paper "bacteria side down" in the guar gum. Then they very carefully peeled off the top "ply" of toilet paper. They put the dish back in to their quart bag and observed the bacteria multiplying over the next several days.

This is my favorite kitchen safety and sanitation activity to date. It was perfect at proving what I wanted, which is:

• Places you think are gross, like bathroom floors or school lunch tables, are the ones most carefully cleaned.
• The dirtiest places are the ones you don't think about like cell phones, back packs, and shoes.
• Sanitize your countertops before starting a lab, even if they appear clean.
• For gosh sakes, put that phone away!!!

Hopefully this recipe puts a fun petri dish surface bacteria activity in reach for your students! Be sure to comment back here to share!

Revisiting Yeast Balloon Blow-Up Activity to Accommodate Latex Allergies

It's back-to school time which means I'm getting a new group of kiddos ready for the kitchen. They are eager to cook (read: eat) but need to understand safety and sanitation first.

In years past I have demonstrated how bacteria multiplies quickly at room temperatures with balloons placed over soda bottles. 

It gives a great visual representation. Recently, however, teachers have been asked to be more aware of students with latex allergies. We have switched our adhesive bandages, gloves, and rubber bands to be latex-free.

I also re-did this activity. Instead of pouring the sugar and yeast mixture into bottles I used quart-sized freezer bags. I squeezed out as much air as possible and continued to follow the same procedure as before.

As you can see, students still have the obvious visual of how much faster bacteria multiplies at room temperature than in a refrigerator. It's just in a more everyone-friendly format.

Throwback Thursday: Kitchen Safety

I found this gem while searching for a bell ringer for food safety. While obviously outdated for my students, I had to share it with someone! The more things change...

Teach Proper Hand Washing Skills with Raw Potatoes: An Update

Some tasty visuals to get you started today... Daily pictures of our handwashing potatoes!

Tuesday:

 Wednesday:

 Thursday:

 Friday:

And the creme de la creme: This morning!

A control potato:

Our cleanest "clean" potato:

And our slimiest, grimiest, dirtiest dirty potato:

Yum, yum!

This is my favorite safety and sanitation activity!  It really grosses out the students.  I find it makes them much more liberal with the hand sanitizer and tolerant of the sanitizing wipes.

These potatoes will still be on the wall for two days...

Here is the link to the original activity.

Remember Symptoms of Food Borne Illness With the Pepto Bismal Dance

I had a student come visit me today.  He was in Food and Nutrition in the first term of my first year teaching.  He needed a copy of my ever-popular monster cookie recipe.

By the way, my monster cookie recipe is AWESOME! I use it to teach measuring skills in Food and Nutrition and have never had a failed batch.

On his way out the door, he asked if I really did the Pepto Bismal dance the day before. Of course I did, and I happily demonstrated it for him.

I teach my kids the Pepto Bismal dance to teach the symptoms of food borne illness.  They think it is hilarious... and very strange.  But they always remember the symptoms!

I found a YouTube video to demonstrate it for you.  Give it a try!

Kitchen Safety Guest Speaker

Today my students enjoyed a guest speaker from the local fire department.  He shared a great example of what water does to a grease fire:

The video also shows a fire extinguishing product that mounts above a stove and drops powder if melted.  It would be a great addition to your classroom kitchens.

Yeast Balloon Blow Up to Demonstrate Bacteria Multiplying at Room Temperature

As part of our discussion on food borne illness, I did an experiment to demonstrate how bacteria multiplies at room temperature.  I got the idea from FightBac.org resources which I told you about yesterday.  I also show it with my Safety and Sanitation Power Point and Numbers to Know Prezi.

Some modifications for this time around...

• I didn't mess with the bowls of water.  I simply left one bottle at room temperature and put one in the fridge.
• I had no sugar so I used corn syrup.  It's a good reminder for students to see what they are drinking in soda!
• I mixed the ingredients right in the bottle instead of messing with a separate beaker.

We observed the bottles at 10 minutes:

20 minutes:

Thirty minutes:

And 45 minutes.

Because bacteria are invisible it is great to have such a visual reminder of the importance of cooling food quickly!

Numbers to Know: Temperatures for Food Safety and Sanitation

I am always surprised at how little students know about temperature.  Last year in Bakery I had my students test their thermometers by placing them in boiling water.  Trouble is, they didn't know what temperature water should be boiling at!

This term in Food and Nutrition I will emphasize temperatures more.  I created this Prezi for a visual.  Students will write the numbers in their study guide and be expected to know them all term.

My Prezi is editable so you can make your own copy.  Some of our textbooks differ in their interpretation of the "Danger Zone" or the exact temperature that meat must be cooked to.

This is a really fun lesson.  I bring freeze pops for the students and talk about freezing temperatures.  We'll do the Prezi and then the Yeast Balloon Blow Up and Cooling Counts activities from the FightBac.org resource. You will find the activities detailed in the 4-8 curriculum.  Although most of my students are Freshman, they still like the visual of the inflated yeast balloons.

Teach Proper Hand Washing With Raw Potatoes

Check out this nastiness on my bulletin board wall!

This activity is one of my favorites and the students really enjoy it too. It is a great way to demonstrate germs that students carry on their hands, even when they appear clean. I used the potato hand washing activity with my Foods and Nutrition students today but the message is simple enough for all ages to understand.

You can purchase chemicals and sprays that make germs on hands “glow,” but those are expensive and unnecessary. All you need for this activity is three potatoes and three sandwich bags.

Begin by peeling the three potatoes (compost the peels!) and scrub them for 30 seconds with hand soap.

Put one potato in a bag as the control.

Pass the next potato around the class. Encourage the students to rub their hands all over the potato.

Demonstrate proper hand washing: Scrubbing nails, tops, bottoms, and betweens, wrists, etc. Also, scrub for a complete 30 seconds.

After the students have touched the “dirty” potato, send the students to the kitchens to practice hand washing.

After the students have washed their hands, pass around the last potato.

We'll be observing these over the next week. I'll keep you posted with updates! (Gross!)

*Update* See daily pictures of the potatoes here.