With this in mind, we have developed an experiment, “Analysis of Barefoot Running.” In this experiment, students use the Goniometer to investigate the biomechanics of barefoot running, a new running trend popularized by Christopher McDougall in the book Born to Run. Traditional running technique emphasizes a heel-to-toe foot strike during each stride. Without the padding provided by traditional running shoes, barefoot running tends to minimize heel strike. This leads to an increase in stride rate, or cadence, of the barefoot runner. As shown in the data below, barefoot running leads to an increase in John’s stride rate when he runs barefoot.

Download “Analysis of Barefoot Running” experiment

LabQuest 2 was the star of the show at a Fieldwork Workshop hosted by the Oregon Forest Resources Institute at the Oregon Garden in Silverton, OR, on a drizzly February day. The workshop highlighted how teachers could get outside and collect data with their students.

Teachers used the Goniometer in an innovative way to measure the height of trees in the Rediscovery Forest at the Oregon Garden. Using the LabQuest 2 in Events with Entry mode, teachers manually entered data in conjunction with recorded data. LabQuest 2 and the Goniometer were used to determine the angle to the top of the tree, calculate the tree height, and record GPS coordinates for later export to a map.

Download the “Finding Tree Height and Diameter” investigation and LabQuest files

Demonstrating fluorescence is a relatively easy method of bringing molecular biology to life. Some molecules, when excited by specific wavelengths of light, will fluoresce by emitting a lower energy photon, as well as heat, as they return to their ground level energy state. This photon has a slightly longer wavelength than the one that excited it. In this case, chlorophyll is excited by blue light and fluoresces red light. In a functioning cell, some of this energy is converted into chemical energy rather than fluorescing. This ability to “harvest” light energy allows them to produce carbohydrates from water and carbon dioxide during photosynthesis.

To prepare a chlorophyll solution, macerate several spinach leaves in a plastic sandwich bag containing 10 to 15 mL of isopropanol. Then pour the contents of the bag through a coffee filter and collect the filtrate. Transfer the filtrate to a 15 mL test tube and stopper it securely. Place it in the BlueView Transilluminator for viewing. The orange plastic lid will filter out the blue light while allowing the red fluorescence to pass through.

The photo shows a BlueView Transilluminator containing three tubes filled with the chlorophyll filtrate. Notice the red glow as the chlorophyll fluoresces from the excitation of the blue light.

This is a great demonstration to perform when your students are conducting the “Plant Pigments” investigation in our Investigating Biology through Inquiry lab book.

Studying vertebrate ecology is an excellent way to explore adaptation and evolution. Mammals and birds are endotherms, meaning they regulate their internal body temperature using metabolic processes. Most other vertebrates are ectotherms, maintaining their body temperature through external sources. Most species of ectotherms are limited to a narrow temperature profile. In contrast, marine mammals have derived characteristics that make it possible for them to maintain their body temperature in different water temperatures. Blubber and fur are two adaptations that provide insulation to marine mammals.

In this experiment using the Surface Temperature Sensor, students explore the properties of blubber and fur. Students attach a Surface Temperature Sensor to a gloved hand, then apply different insulating materials, such as shortening and bubble wrap. They submerge their hand in ice water and collect data to determine temperature change over time.

Vegetable shortening and bubble wrap mimic blubber and fur. Vegetable shortening has a much lower thermal conductivity than water, so its thermal properties make it analogous to blubber. Bubble wrap is composed of numerous pockets of trapped air, so its thermal properties should resemble the fur of a polar bear or sea otter. Bubble wrap is a cheap and accessible material to use as a stand in for fur or hair.

Have your students design their own insulating gloves to turn this lab into an engineering opportunity. Consider using natural limits and constraints in nature to shape the constraints of their design.

Download Insulation in Marine Animals lab instructions

The following procedure describes how to configure Logger Pro so that a Vernier Motion Detector monitors an area and turns on a buzzer when a person enters.

1. Connect the buzzer to line 1 of the DCU.
2. Connect the DCU (with power supply) to the digital (DIG 1) port of the interface and the Motion Detector to the digital (DIG 2) port.

   
   
   
   

3. Configure Logger Pro.
   1. Choose Set Up Sensors from the Experiment menu, and then select your interface.
   2. Click DIG/SONIC 1 and select Choose Sensor ▶ Digital Control Unit.

      
      
      
      

4. Configure the DCU.
   1. Click DIG/SONIC 1 a second time and select Digital Out.
   2. Select the Activate Line 1 check box.
   3. Select Less Than or Equal To (≤) and enter a threshold value, such as 1 meter.
   4. Select the check box next to Start activation when experiment run is started. Data collection begins when you click .
   5. Click OK and close the Set Up Sensors configuration window.
5. Click to start data collection. When someone passes within 1 meter of the Motion Detector, the buzzer should turn on.

To see the proximity alarm in action, as well as seeing Dave Vernier take on the challenge of creating an automated tea maker, check out the video below:

By using split sources of radiation, students can determine the resolving time, T, by measuring the observed count rates of each source individually and then as a combined source.

Download Richard’s lab instructions for determining the resolving time of a Geiger-Müller tube

The Radiation Monitor is mounted on a wooden stand, and the radioactive source is mounted a set distance from the G-M tube end window. Radiation counts are collected for ten one-minute intervals each for background, Sr-90, and Co-60. By using the number of detected counts for the radiation source and the known number of radiation disintegrations from the source, students can calculate the efficiency of the G-M tube.

Download Richard’s lab instructions for determining the efficiency of a Geiger-Müller tube

A few years ago, there was a flurry of news stories warning of the dangers of radioactive granite countertops. Often caused by misinterpreted data, these claims led to public outcry and prompted the EPA to put together an FAQ regarding radioactivity in granite countertops.

Richard Born of Northern Illinois University used the new Vernier Radiation Monitor to test the radiation counts above a wooden table and a granite countertop. The counts for the granite countertop were higher, but does that make them unsafe? There are currently no regulations concerning radiation emissions from granite countertops. How do your countertops compare to the ones tested by Dr. Born?

As you can see from the graph, the larger unit uses more energy per unit of time and completes the charge cycle more quickly. But is it the same total amount of energy? To find out, we integrated under each curve.

The energy required to fully charge the battery is about the same, but there is a small difference. We did not measure temperature in this experiment. From what we have learned about rechargeable batteries in the last few years, we know that charging at a higher current generates more heat, which makes the charging process less efficient. Some people believe that consistently charging the battery at higher current can shorten its overall life. Other aspects to investigate:

• Temperature
• Off-brand chargers
• Charging while the device is on or off
• Comparing the charge cycle of different phones and tablets
• Estimating the cost of the energy to charge electronics such as laptops and tablets

Note that for loads lower than about 5 watts, the Watts Up Pro is not nearly as accurate as it is for household appliances such as refrigerators, freezers, and air conditioners.

We can use the SpectroVis Plus spectrophotometer’s fluorescence function to observe Riboflavin in energy drinks. This same technique can be used to investigate the concentration of vitamin B2 in vitamin tablets, foods, and other beverages.

Fluorescence is the emission of light by a compound after it has absorbed a particular wavelength of light. Under most circumstances, the emission of light will occur at a longer wavelength than the light used to excite it. The SpectroVis Plus has two excitation wavelengths, one at 405 nm and 500 nm.

To analyze the concentration of vitamin B2 in an energy drink, such as Rockstar Sugar-free, transfer a small sample of beverage into a cuvette. Make sure that all the bubbles from the carbonation are gone or are out of the pathlength of the white light. Set the SpectroVis Plus to Fluorescence mode with excitation at 500 nm. Collect a spectrum. You should observe at least one peak, with its maximum at 550 nm. If a narrow peak is observed at 500 nm, it is merely scatter from the excitation source. The emission spectrum will contain the emission from Riboflavin.

To verify that the peak is Riboflavin, have your students prepare a standard solution that contains a known source of the compound. It is best to purchase Riboflavin from a chemical company for the most accurate and quantitative results. You can also purchase vitamin B2 tablets at the supermarket and get nice, qualitative results. Dissolve a known mass of Riboflavin in 1% acetic acid in water (diluted vinegar or sparkling water can also work as a solvent). If you are extracting the compound from a vitamin tablet, it is recommended that you filter the solution before use. Dilute this standard solution appropriately to a fluorescence value of approximately 0.5 at its peak wavelength above 510 nm. You should see a peak that looks similar to the one from the energy drink. Keep in mind that some energy drinks may not have a high enough concentration of vitamin B2 to be seen in a fluorescence spectrum. Rockstar Sugar-free works nicely and offers a great starting point to see if other beverages that are relatively translucent have vitamin B2 present.

Quantifying Riboflavin with Fluorescence

Due to the high fluorescence quantum yield of Riboflavin, it is also interesting to have your students perform a calibration curve with a similar set of standards using the fluorescence function of SpectroVis Plus. Because Riboflavin peaks at 440 nm, it is appropriate to use either excitation wavelength 405 nm or 500 nm. The data shown was obtained with excitation at 500nm. Excitation at 500 nm exhibits an emission peak at 550 nm. Since the absorbance is so low at this wavelength, the standards should not need to be diluted. Be aware that a calibration curve of the fluorescence of this compound may begin to curve because of self-absorbing; use only the linear region of the calibration curve for analysis.

Monitor the fluorescence value of your energy drink at 550 nm and compare this to your standard calibration curve. At low enough concentrations, the relationship between fluorescence and concentration reduces to a Beer’s law-type analysis. Just keep in mind, that all comparisons this way will be relative and not absolute.

Use this idea as a great way to incorporate fluorescence spectroscopy into your chemistry and biochemistry curriculum; it works particularly well as an inquiry-based experiment.