Collecting maple sap for the production of maple syrup is the ideal project for any teacher looking to bring the classroom outdoors. "But I don't live in the North East" you say... Well guess what, neither do I! I work as a middle school science teacher in Winston-Salem NC and have had a very successful season with my students. Anyone can follow this plan, and nothing beats a lesson that ends in eating sugar out of a tree.
The educational lessons captured in this simple project include but are not limited to; weather observations and prediction, the water cycle, conduction, convection, pressure differences, ratios (sap to syrup), measurements, conversions, species identification... Just to name a few. I offered this project to a few students from each class as an option for their STEAM (science, technology, engineering, arts, math) project. I wanted all of my students to participate in some type of year long project and the collection of maple sap fit perfectly.
Students can also create a video journal of their experience. Here is the video that my students created:
Step 1: Maple Syrup in the Classroom
- Maple trees (minimum 12 inch diameter)
- cordless drill
- 7/16" drill bit
- buckets (metal or plastic)
- lids for the buckets
- heat source
- big pot for boiling the sap
- restaurant grade filter paper / coffee filter / clean felt (to strain out any particulates)
- 5 gallon bucket (for transporting the sap)
I ordered all materials from www.tapmytrees.com. They were super helpful and I couldn't be happier with experience from start to finish. They sell a teaching kit that comes with everything you need (minus the trees!).
There are many different ways to collect and process the sap, but this instructable outlines the way I do it (which works for me). A quick search may turn up a method that works better for you (or your students). Make your students do the research!
Step 2: Tree Identification
In the Fall, when leaves were at peak foliage, I had students walk campus to identify the different types of trees. They used an iPad app called leaf snap to help them. The app wasn't that great, but it helped. They discovered we had sugar maples, black maples, and silver maples on campus.
One of the requirements for tapping a maple tree is that it must be at least 12 inches in diameter. Students used a flexible tape measure to discover the circumpherence. Once they knew the circumference, they got to do some math. The formula for calculating diameter of a circle when you know the circumference is:
Diameter = Circumference / Pi
A general rule of thumb for tapping trees is 12"-21" = 1 tap, 21"-27" = 2 taps,
The students then marked off the trees with rope. An additional recommendation is to create a tree map to help document different varieties on your campus.
Step 3: Tap Your Trees
When the weather is right, it's time to tap your trees. How do you know when the weather is right? When the night time temperatures drop below freezing and the daytime temperatures go above freezing. In more northern climates, this tends to happen in late winter or early spring. In Winston-Salem, we were able to start in early January. The science behind why the sap starts to flow has to do with differences in pressure between the trunk of the tree and the roots due to uneven heating.
To tap the tree:
- Pick a spot on the tree about 3 feet from the ground. A spot on the south side of the tree and above a big root seems to work well.
- Using the 7/16" drill bit, drill a hole at a slightly upward angle 2" - 2.5" deep. It's a good idea to mark off the desired depth mark on the bit with a piece of tape. The upward angle helps facilitate the flow of sap down the spile.
- Remove as many wood shavings as possible from the hole.
- Place the hook over the spile and gently tap the spile into the tree with a hammer.
- Add the bucket with the lid onto the hook.
- Sit back and watch the weather forecast.
Step 4: Collecting Sap
Depending on the temperature fluctuations, some days the buckets will be full and others... not so much. The sap can go bad so it must remain cool. I treat it like milk. If it's cold enough outside, I can just leave it the sap in the buckets on the tree. If the temps are heading into the 50's, I collect the sap and either boil it down in class or refrigerate it until I have a descent amount. I have a few 5 gallon buckets with lids that my students use to transfer the sap back to class.
Carrying full 5 gallon buckets can be tough for even the strongest 7th graders. I have created a team building exercise where my class breaks down into two even lines. The two students at the front of the line each put a hand on the handle of the bucket and carry the sap far as they are able/willing. When they are tired, they place the bucket gently on the ground and peel off to the back of the line to await their next turn. The next two pick up the bucket and the procession continues. It's sort of like a ruck walk.
The sap should be boiled before consumption, but I am a bit of a risk taker and enjoy drinking it straight from the bucket. To me, it tastes a bit like coconut water. It's slightly sweet... But pretty much it's just water. It's awesome to see the students try it for the first time and get so disappointed that it doesn't taste like syrup. Good things come to those who wait.
One of the neatest things we observed was that despite the cold temperatures, honeybees will find their way to the sap (We also keep bees on campus). Another interesting thing we noticed is that the amount of sap in a bucket varies greatly... even two buckets on the same tree can have completely different amounts of sap in the same 24 hour period.
Step 5: Making Syrup
First, understand you are preparing a food product and caution should be taken. All cooking utensils should be cleaned thoroughly beforehand to ensure sterilization. Due to the high sugar content, the sap is an optimal breeding ground for bacteria.
Next, understand that it takes a good bit of energy to boil all of your sap. This might be a good teachable moment for your students. The ratio of sap to syrup is about 40:1. That means 40 gallons of sap will produce 1 gallon of syrup. I had my students answer this question as a warm up, "If I have 4 liters of sap, how many milliliters of syrup can I expect to obtain?" Then I show them a beaker with 100 mL of water. It's a significant difference. The end product, in my opinion, is well worth the energy spent.
Collecting sap at school has its advantages. We happen to have a very supportive kitchen staff who are willing to help us boil down the sap. They have a much more powerful range and giant pots to get the job done much more quickly than the hot plate in my science classroom. Plus, if you boil gallons and gallons of sap in class your students get to see and feel first hand what happens to the water vapor in the room (it's not always a good thing when your posters start falling off the walls and it feels like a rainforest).
Making syrup is is as easy as boiling water. No really, it is. The hardest part is when you get close to finishing. You could purchase a candy thermometer or a hydrometer to make sure it's perfect, but the spoon dip method works fine for me. When the syrup coats the apron of the spoon instead of running off like water, it's done. At this point, while the syrup is still hot, you will want to run it through some filter paper to remove any particulates. Once the syrup has been filtered, add the finished product to a clean bottle and store it in the fridge.
Step 6: Finished Product
I know it's tough, but don't forget to share your syrup. Make sure you let me know how it goes.
At at the end of the season, when the temps stay above freezing at night and the trees start budding, it's time to remove the spiles. Clean all materials thoroughly and save for next season. The tree will heal itself. There is no need to try to plug the hole. It's not a bad idea to give the tapped tree a break the following season. If tapping the tree every other season is not an option, drill the new hole over three inches and up or down five inches from the previous tap hole.