How Efficient are Drinking Taps?
Students devise an experiment to measure the amount of water consumed at a drinking fountain, in relation to the amount wasted. The results are then extrapolated to estimate the amount of water wasted per student each day, per school each day and for 100 schools each day.
The instructions provided to the students are:How efficient are our drinking taps?
- Discuss with your partner what this means and what you intend to do.
- What equipment will you use and why?
- What is your step by step procedure?
- What results did you get? Show your maths calculations.
- How much water was wasted for:
How much water would be wasted for 3 drinks per day (one student)?
How much water would be wasted per day if there were 300 students at school?
How much water would be wasted per day over 100 schools?
Key Mathematical Concepts
- Conversion of units
- Data collection and analysis
- Problem solving skills
- Working mathematically
Students need to be able to convert metric units of measure.
Links to VELSDimension / Standard
Measurement, Chance and Data (Level 4) /
- Students use metric units to estimate and measure…volume, capacity…They measure as accurately as needed for the purpose of the activity. They convert between metric units of…capacity…(for example, L–mL…).
Working Mathematically (Level 4) /
- Identification of the mathematical information needed to solve a problem or carry out an investigation.
- Communication of the results of a mathematical investigation in an appropriate form.
To be working at Level 4, it is assumed that students will devise a well considered experiment to determine how much water is wasted from a drinking fountain. It is expected that students will choose to use an appropriate measure (volume) for their calculations, and will report their findings using the most appropriate units.
Students need to demonstrate an understanding of how to extrapolate their findings for a single sample to a larger number of events.
The student work sample (below) that demonstrates this is number 1.
Potential Student Difficulties
Attention by students to following the written instructions in a multi-step activity such as this is necessary, and not all students in the trial managed this aspect of the task.
Some students experienced difficulty in extrapolating the water loss results for a single drink to multiple drinks.
Possible Enabling Prompts
Some suggested prompts to assist students experiencing difficulty in starting the activity:
- How much water comes out of the drinking fountain in 10 seconds?
- How much water is there in a small glass?
For students who would benefit from additional challenges:
- Make a list that identifies anything that reduces the accuracy of your results. Do you think these things will lead to large errors or small errors? How might you redesign the experiment to overcome these?
- Consider how you might generalise your findings, so that a water company could use your figures to calculate water wastage from drinking fountains across Melbourne.
Students in the trial reported that this activity was fun and identified a main learning outcome as being greater understanding of the environmental context of water wastage.
A variety of approaches was taken by students in the trial to the design of the data collection methodology, some with greater success than others. The varying approaches to analysing results yielded quite different answers in some cases (some students measured the weight of water, others measured volume of water). One pair of students extended the question to an emerging concept of rate of water wastage per person. Most students did not consider whether a single sample would be an adequate representation of all people’s drinking habits, and whether all drinking fountains flowed at the same rate.
This activity provides teachers with an excellent insight into their students’ ability to solve problems and work mathematically.
The open-ended nature of this activity means there are many correct solutions. However, Student Work Example 1 provides an excellent illustration of a suitable approach to the problem.
How Efficient are Drinking Taps?
Student Work Samples
Working at VELS Level 4
Not yet working at VELS level 4