Chemistry: pH scales and acidity

DiScoro writes about inquiry-based learning, digital resources, and ways to encourage higher-order thinking. We focus on STEM education and the use of technology.

The PHET simulation pH Scales enables students to experiment with acidic and basic fluids.

Note that pH scale and acidity are complex concepts for students especially for primary school pupils. A lower pH value means more ‘acidic’ and a higher value means less acidic, or more ‘basic’.  Neutral is indicated by the pH value 7.0.

However, the simulation can help the students to familiarize themselves with the concept(s). The simulation can be used in grade 6 or 7. Depending on how much time you wish to spend and how much structure you wish to give, in addition to the simulation, you could encourage the students to experiment and discover the basics about pH values in fluids and its application in every day life.

Suggestions for tasks and experiments:

  1. Check out the different fluids available.
    Rank the fluids from most basic to most acidic before you start measuring. Write down your estimation.
  2. Measure the pH values for the fluids given and write the results in a table.
    Which fluids are closest to pH 7.0?
    What does it mean if  the pH value of a fluid is close to 7.0?
  3. Use water to dillute the fluids and try to make a fluid that is closest to 7.0.
    Write down what you have done to reach your result.
    Make a screencast of your closest result(s) and print it out.
  4. Can you dillute a basic fluid with water to a pH value below 7.0?
    Can you dillute an acid fluid with water to a pH value above 7.0?
    Try to explain the result?

Think beyond the simulation.

  1. How could you make an acidic fluid basic? In other words, how could you for example change the pH value of an acidic fluid from 5.0 to 7.5?
  2. a. Your body functions best if the pH value is neutral. How does your body manage this?
    b. With the knowledge about the pH value of your body, how can you support your body to remain healthy?

pH value paper strips

In addition to the simulation students could use pH paper strips to measure the acidity of fluids. It becomes particularly interesting if the fluids you use can be tasted. Students can describe the taste they experience. Use for example coca cola or other fizzy drinks, fruit juice, tea, milk, coffee, water. This real life experiment makes it possible to neutralise an acid/basic fluid using other chemicals, for example by adding bicarbonate (baking soda) to an acidic fluid.

battery hydrometer

Another interesting tool is a battery gravity hydrometer, which actually measures the acidity (pH value) of the battery acid. You could also say that it measures the gravity of the battery fluid. Together with a Volt meter it is used to check if the battery is charged and in good condition If your battery is fully charged the pH value should be near 1.28. If the battery is discharged, the pH value will be near 1.14. The battery hydrometer only measures accurate with pH values around 1.2. So is useless to measure pH values over 2.

More PHET simulations. See also Balancing Act, The moving man, Energy skate park, and Density and Buoyancy.

 Purchase  Free
 Hardware  PC, iPad
 Requirements  browser
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Gossip Simulation

DiScoro writes about inquiry-based learning, digital resources, and ways to encourage higher-order thinking. We focus on STEM education and the use of technology.

The Gossip Simulation shows how fast gossip spreads through a group of a hundred people. The simulation enables the user to change the number of people that start to spread a message. Besides the variable number of initial processes (= number of people) there is the variable message loss. The value behind message loss can be attributed to different factors. It could for example be based on the percentage of the people that is not likely to pass on the message.

After the students have familiarised themselves a little with the simulation, you as a teacher could discuss what (other) reasons may lie behind the variable message loss.
The value will be different when the message is a secret and when people are being asked to keep the secret, than when the message contains interesting but harmless information. The value of message loss will also vary in different groups . Some people may be too busy, ill, travelling and are therefore not communicating intensively within the group for a while. There are more factors that could influence the value of message loss.

To explore the simulation students could be asked technical/mathematical questions such as:

  • How many rounds does it take before everyone has got the message with x processes and a message loss of y?
  • Why is the outcome not exactly the same if you run the program several times with the same values for the variables?
  • Can you calculated/estimate the amount of rounds it takes? Explain how and what you did?
  • How could you extrapolate to a thousand people, or to the whole population?

The simulation could be used to discuss group behaviour in real life and on social media. Also topics related to safety/security systems based on communication could be discussed. Warnings about oncoming disasters (tyfoon, floods, earthquakes, pollution etc.) and messages related to evacuations need to reach as many people in a short timespan.

Additional questions for students could be:

  • Considering different scenarios, what could the rounds represent? (minutes, hours, days, weeks ….)
  • When is rounds more likely to be days than minutes?
  • If you want to prevent a message to spread on Facebook, how could you prevent or stop this?
  • What else could this model represent? (spread of warning, spread of a disease, spread of a product, ….)
  • Could you come up with a better name for the simulation.
  • If the police wishes to spread a warning as fast as possible, how could they best go about it?
  • In what way could you use this model to visualise a disease from spreading too fast?

Proposed age group: grade 5-10.

 Purchase  Free
 Hardware  PC, iPad
 Requirements  Browser

Simulation: Diversity

DiScoro writes about inquiry-based learning, digital resources, and ways to encourage higher-order thinking. We focus on STEM education and the use of technology.


This blog is about two simulations based on the same concept namely Thomas Schelling’s Model of Segregation. The model tries to explain social phenomena and shows for example how difficult is it to build and sustain a diverse community. Schelling tries to explain when and why ghetto forming takes place and under which conditions this can be prevented or even reversed.
In other words, people with shared identities tend to cluster/group together. In most classes boys and girls form their own groups.

The first simulation by Frank McCown is named Schelling’s Model of Segregation. The second is by Vi Hart and Nicky Case and named Parable of the Polygons. The two simulations have different interfaces. Both simulations use two groups. The first simulation has four variables (and a interval timer) whereas the Parable of the Polygons offers different simulations for different variables.

The simulation by Frank McCown can be found if you scroll down on the page. The simulation generates a multitude of questions that can be explored.

    • When do communities remain diverse?
    • When and why does clustering take place even if people are relatively tolerant and open-minded?
    • Can segregated communities be tolerant?
    • Under what circumstances does segregation happen and why?
    • How can a segregated community become diverse?

The Parable of the Polygons contains a group of simulations and uses scaffolding to explore the concept. Contrary to Mc Cown’s simulation the Parable of the Polygons visualise if people are happy or not. Additionally the user can move ONE person and see what happens. The last simulation is a particular interesting one.

 

The Parable of the Polygons could be used as inspiration for the teacher. However, in our opinion the degree of scaffolding will limit the curiosity, thinking and reasoning by the students themselves.

As teachers we have to be careful how to introduce the simulation and how to discuss the issues. Minority groups in class can easily feel uncomfortable. It is up to the teacher to choose the context and vocabulary that suits the class. As you may have observed have we tried to use the word diversity instead of segregation.

Additionally, the simulations can be used by policy makers, but also by students in relation with religion, geography/demography. It has been known in chemistry that seperate molecules and molecules in small quantities react differently than in mass. The same can be observed with people. Individual people can be tolerant and open-minded, but the large group will nevertheless become clustered under certain conditions.

 

 Purchase  Free
 Hardware  PC, iPad
 Requirements  Browser

Technology and Design – Rocking horse

DiScoro writes about inquiry-based learning, digital resources, and ways to encourage higher-order thinking. We focus on STEM education and the use of technology.

We give an example of  a Technology & Design task. In several countries Technology & Design is a (project based) school subject for students (grade 6 to 10). This task comprises many subjects: arts, mathematics (measuring, scale and ratio, geometry) physics (friction, mass, centre of gravity, forces, movement), language (vocabulary, writing skills), technology. In addition, it is an example of co-creation and collaboration.

Task: design and make a rocking horse for young children
and test out it at a kindergarten.

The task is complex and challenging, yet at the same time has a very clear goal. We discern different steps.

(1) Research and design of rocking horses. Students may search the internet for ideas, examples, pictures. The students may check out different constructions, materials used. Students can search for technical drawings or draw the design from scratch. Others may want to build a miniature modell. At the end of this step the students have made their choice about what material they will use and about the type of construction.

Examples of rocking horses from the internet

(2) Planning. What are the steps to take in de construction phase? What do I need for the construction in terms of material, tools, and other resources. How much time do I need? What are the costs?

(3) Implementation. This will be carried out in the planned steps. A prototype made of cardboard or plywood (3mm or 5 mm) can be useful. If not a design on paper 2D/3D is required.

technical drawing on scale
colour test
template in cardboard
miniature prototype
cutted parts
final product

(4) Test at kindergarten. Students should decide in advance WHAT they will test out. (e.g. Is the construction strong enough? Is the the rocking horse attractive for the children? What age group does it suit best? Is it safe in use? Does it swing enough?) and HOW they will test this out.
The students will have to plan a visit to a kindergarten and explain what they wish to do. The results must be reported.

(5) Reporting and documentation. This should be done during the whole process and not just only at the end. Students may choose if they wish to use mainly written or oral, visual, or multi-media  documentation for reporting. The teacher could (or  should) specify what he/she expects and how it should be presented/delivered.

Of course the rocking horses could be examined, measured, compared in many ways and from different perspectives (physics, accounting/economics, maths).

Technology and Design

DiScoro writes about inquiry-based learning, digital resources, and ways to encourage higher-order thinking. We focus on STEM education and the use of technology.

This time we write about Technology & Design as a school subject or project for students (grade 6 to 10). In several countries Technology and Design has become a school subject.
Most commonly students work on a task during more than one hour. The tasks are interdisciplinary and require many different skills: planning, sketching, creativity, safety, use of tools, research , construction, experimentation etc.
Technology is not limited to the use of digital technology. Technology & Design tasks have a strong practical component and aim at problem solving skills. By nature the tasks are often low floor-high ceiling tasks. This implies that it is clearly understandable what the goal is, all students are able to get started (low floor). At the same time the tasks offer enough challenges and opportunities to dive deeper both in creativity as well as in complexity (high ceiling).

To make a plan is usually a step in the process. It is up to the teacher to ask for a report of the process or not. This can be written, visual, oral, with the use of multi-media (photos, video) or a combination.

Topics that could be part of Technology & Design are

    • design and create a rocking horse for children age 2-3
    • make a piece of household furniture using recycled materials
    • make a gripper stick for waste picking, or for elderly people at their homes
  • engineering (using concepts from chemistry and physics)

Technology and Design will certainly focus on the new economy where circular design and production, and no or minimal waste, are the ultimate challenges and goals.

Lux Meter App

DiScoro writes about inquiry-based learning, digital resources, and ways to encourage higher-order thinking. We focus on STEM education and the use of technology.

A phone with a camera has an built-in light sensor. This makes it possible to use your camera as a Lux meter. Lux meters on smartphones are an easy, accessible and cheap way to measure illumination.

Galactica is a lux meter that can measure light in to modes: direct and reflected. You can save measurements as photos and add a note.

Is a Lux meter on your smartphone reliable? Read the following blog Luxmeter App vs measuring device on research carried out with different smartphones and with different software. The conclusion is that for accurate and consistent measurements you need professional equipment and software.

Reflected light measurement
Direct light measurement

However, to get an idea about light intensity the lux meters function well. The reflection mode offers the opportunity to see how the colour of a surface reflects or absorbs light. An interesting experiment is with a static lamp shining on a tabletop. Put paper sheets of different colours on the table and measure the light that is reflected by each colour. The results are quite remarkable.

Hardware and software with sensors for light, noise and temperature designed specifically for educational purposes is  €Sense. This package offers activities/lessons in which the sensors are used. Read more about €Sense (Euro Sense).

There are many lux meters available for iOS as well as for Android.

 Purchase  Free
 Hardware  iPhone, iPad
 Requirements  iOS 6  or higher

Noise Exposure

DiScoro writes about inquiry-based learning, digital resources, and ways to encourage higher-order thinking. We focus on STEM education and the use of technology.

We wrote about a Decibel meter App which measures noise level in decibel before. Noise Exposure is another App that measures the noise level in decibel. Noise Exposure has a simpler user interface than Decibel meter thus can easily be used with primary school pupils. An advantage is that you can save and share measurements. This makes it easier to register and compare measurements.

 Purchase  Free
 Hardware  iPhone, iPad
 Requirements  iOS 8 or higher