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# Biology Experiments and the TimeLapse Pro iPad App

Teachers can easily incorporate iPads into their biology science classrooms to research and record experiments. This activity uses iPads and the TimeLapse Pro app to measure the growth of mung beans over time.

 Submitted by Sam Gliksman Grade level 4th- to 6th-grade science Objectives Students learn to measure and collect data about botany and plant growth, and learn simple techniques for statistical mapping and mathematical analysis. Apps/tools iPad 2 (or higher), time-lapse photography app such as TimeLapse Pro or StopMotion Recorder, photography stand for iPad, Numbers app Materials needed Packet of mung beans, 4 glass jars or beakers filled 75% high with sterilized potting soil, tap water, salt, dish detergent, coffee powder, 4 100ml beakers, 1 measuring cylinder, 1 digital weighing scale, black marker and/or labels

This experiment uses TimeLapse Pro to test how different solutions used to water plants affect growth. The results will be measured and recorded by students while also being captured on time-lapse video.

The following points outline the process:

• The independent variable is the solution used to water the plants — plain water, coffee-and-water mixture, salt water, and water-and-detergent solution.

• The dependent variable is the growth of the mung-bean plants. This is determined by measuring the height of the plants every day.

• The constants (control variables) are the size of the container, the amount and concentration of the various solutions added daily, the amount of sunlight, and the temperature of the environment (room temperature).

• Fill the four glass jars or beakers three fourths full with the sterilized soil. Plant 12 mung beans in each pot, and allow them to germinate for 5 days, using the same amount of water on each plant.

You need ten seeds to germinate; add two extra just in case some don’t germinate. When you are ready to record your data, make sure you have only ten germinated beans.)

• Plug in the iPad, mount it on a stand, and set up your TimeLapse app. Set the time lapse to take one picture every five minutes.

For the first five days, you may choose to do a close-up of just one of the plants to capture the mung-bean germination in full close-up. The resultant time-lapse movie is truly magical.

• After the first five days of germination, you need to have a clear view of all four plants so that you can compare the growth of the plants and the effect of the different solutions. Make sure that you are looking at them from the same angle so that perspective will not be a factor.

• Water the four plants with tap water only for the first five days, allowing the seeds to germinate. After five days, record the average heights in a spreadsheet in the Numbers app.

Discuss the meaning of “average” growth and how it can be calculated in the spreadsheet. Obtain the average height by measuring the height of the ten plants in each pot, adding them up, and dividing by 10.

• Prepare your four solutions in the 100ml beakers. For the coffee mixture, add 10g of coffee to 100ml of water, and label it Coffee. For the detergent mixture, mix 10ml of detergent to 100ml of water, and for the saline solution. add 1 g of salt to 100ml of water. Label each beaker accordingly.

You could also prepare enough solution in advance for all ten days by preparing a liter of each of the mixtures.

• Label the four plants Water, Coffee, Detergent, and Saline. Over the next ten days, water the pots once a day with 100ml of each solution, according to the labels on the pots.

Make sure you turn the plants halfway through the experiment period to ensure that each side of the plant is getting adequate sunshine.

Check to make sure that the soil is not too soggy and there is no water pooling at the bottom of the container. Adjust the quantity of liquid if need be, but be sure to give each plant the same amount of liquid as the others.

• Measure and calculate the average height of the mung-bean plants every day for the next ten days. Record all calculations in a Numbers spreadsheet.

• Discuss linear graphs and their meaning; then have the students use the different growth rates to create a linear graph.