The purpose of this resource is to teach students about the acidity levels of liquids and other substances around their school so they understand what pH levels tell us about the environment. Students will create mixtures of water samples, soil samples, plants and other natural materials to better understand the importance of pH levels. Educational levels: Primary elementary, Intermediate elementary, Middle school, High school

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

English

Digital Library for Earth System Education

GLOBE® 2005  The pH Game Learning Activity - 1 Hydrology
A
ppendix
W
elcom
e
Introduction
Protocols
Learning A
ctivities
The pH Game
Purpose 
To teach students about the acidity levels of 
liquids and other substances around their school 
so they understand what pH levels tell us about 
the environment
Overview 
The pH game will engage students in the 
measurement of the pH of water samples, soil 
samples, plants and other natural materials from 
different places. Students will create mixtures 
of materials in order to collect different pH 
measurements.
Student Outcomes
Students will identify the pH of common 
substances, learn how high or low pH levels 
may result in dangerous conditions in the 
environment, and examine how pH may be 
changed.
Earth and Space Science
Water is a solvent.
Each element moves among different 
reservoirs (biosphere, lithosphere, 
atmosphere, hydrosphere).
Physical Science
Objects have observable properties.
!
?
Scientific Inquiry Abilities
Develop explanations using observations.
Recognize and analyze alternative 
explanations.
Communicate procedures and 
explanations.
Use instruments to gather data 
accurately.
Time
One class period for preparation
One class period for the game
Level 
All
Materials and Tools
For each team: (about 4 students)
 20 pH strips
 3 to 5 small cups
 Paper and pencil
 Labels to attach results to results 
board
For the class:
 Results board (one line of pH levels 
from 2 to 9 for each team)
 Flip chart with rules
 Additional pH strips
 Cups of solutions prepared for 
analysis
Preparation
Gather materials for pH solutions.
Prerequisites
Discussion of lab safety procedures
GLOBE® 2005  The pH Game Learning Activity - 2 Hydrology
Teacher Support
Introduction
The level of acidity (pH) significantly influences 
the vegetation and wildlife in an environment. The 
pH can be influenced by different factors. The main 
natural influences are the contributions from rocks 
and soils. Human activities can also contribute, 
by releasing basic or acidic substances into the 
air, water or ground. One particularly important 
contribution from human activities is acid rain 
(which forms when acidic compounds released 
into air combine with water in the atmosphere). 
Acid rain can lower the pH in water bodies to levels 
that are dangerous to certain species. 
It is important to understand pH. This activity 
will help your students understand the pH scale. 
More advanced students will mix acid and basic 
solutions to produce solutions of intermediate pH, 
and will also learn about the relationship between 
alkalinity and pH.
Advance Preparation 
You or your students should prepare various 
acidic and basic mixtures/solutions of natural 
and processed materials. These solutions should 
be labeled with the ingredients and a letter, but 
not their acidic or basic characteristic. Examples 
of acidic solutions include fermented grass, 
dilute and concentrated lemon juice, black 
coffee, vinegar, orange juice, and soft drinks. 
Basic solutions include salt water, shampoo, 
baking soda, chlorine bleach, household 
ammonia, and oven cleaner. Local water and 
soil solutions should be used as well. Soil 
water solutions are produced by mixing equal 
amounts of distilled water with soil, and then 
allow the soil particles to settle out. You can also 
produce solutions from materials found around 
the local school area, such as oil drippings from 
a vehicle, liquid in a discarded bottle, etc. 
pH Value
Teams 2 3 4 5 6 7 8 9  TOTAL
Team 1
Team 2
Team 3
Table HY-pH-1
pH Value
Teams 2 3 4 5 6 7 8 9  TOTAL
Team 1 1  1   1 1  4
Team 2  1  1    1 3
Team 3 1    1  1  3
Table HY-pH-2
GLOBE® 2005  The pH Game Learning Activity - 3 Hydrology
A
ppendix
W
elcom
e
Introduction
Protocols
Learning A
ctivities
What to Do and How to Do It
Remind students of the difference between 
hypothesis and results. Encourage them to develop 
their hypothesis and find a way to test it with 
results. The Implementation Guide for Teachers in 
the GLOBE Teachers Guide contains materials on 
guiding students in research. Divide your class 
into separate teams. 
The Rules 
1. Explain that the objective of the game is 
for each team to identify solutions that 
have a pH range of 2-9. 
 The students should draw a horizontal 
pH scale line from 0 to 14, marking pH 7 
as the neutral point. Each unit should be 
spaced at least 1 cm apart. They should 
then draw a box underneath each pH 
unit from 2 to 9. 
 Each team finds substances that have 
a pH corresponding to a box in the pH 
scale. 
2. The teacher draws the following matrix 
on the board. See HY-pH-1. 
3. One point is awarded for each box filled, 
even if the team finds two samples with 
the same pH. 
4. Students should record all the 
information about the solution from the 
labels and the pH they measured. 
5. When students are ready to submit a 
sample for the game results board, they 
show the teacher their notes and sample. 
Together they measure the pH with a 
new pH strip. If the pH agrees with the 
students’ previous measurement, the 
sample is approved and the points are 
added to the team’s score. The Table HY-
pH-2 is an example of results for different 
teams. 
6. The teacher gives a new pH strip for each 
sample added to the results board. 
 
Extensions to the pH Game
Beginning 
For a basic understanding, use salt and sugar and 
explain to students that salty does not necessarily 
mean acid and that sweet does not necessarily 
mean basic. Cola soft drinks are good examples 
of a sweet and very acid liquid. 
Intermediate 
Make the game more competitive. For instance, 
the team that finds or creates the first sample of a 
particular pH value receives 5 points; subsequently, 
samples for that pH level receive only 1 point. 
Make the game more difficult by limiting the 
sample sources to only natural materials. 
Limit the number of pH strips given to each 
group and set up a rule for buying a new one 
with game points. 
Advanced 
Ask the student which solutions should be mixed 
together to produce a neutral solution (pH ~7). 
Explain to the students that pH is a logarithmic 
scale and is not additive. (For example, mixing 
equal amounts of unbuffered solution of pH 6 
and pH 7 would produce a solution of pH 6.2, 
not pH 6.5, although if they are using pH paper, 
they will not be able to tell the difference.). Have 
them test their hypothesis by mixing some of the 
labeled solutions together and recording the pH. 
How much of each solution was used? What was 
the resulting pH? Is it higher or lower than then 
expected?
Explain the concept of acid neutralizing capacity 
(alkalinity). Discuss whether it requires more 
acidic solution to lower the pH of a solution with 
high alkalinity or a solution with low alkalinity, 
when both solutions have the same starting 
pH. Many of the solutions may have some 
alkalinity; therefore a higher proportion of the 
acidic solution will be required to lower the 
pH of the solution with higher alkalinity. Have 
students discuss the neutralization capacity of 
the different solutions. Relate this to buffering 
capacity (alkalinity) of hydrology sites. 
Conduct a similar analysis of samples made from 
water from different areas of your community. 
GLOBE® 2005  The pH Game Learning Activity - 4 Hydrology
Compare tap water compare with water from 
your study site. Compare the pH of water mixed 
with soil from different soil horizons.
Note: For older students we recommend inviting 
an expert to answer their questions. 
Further Investigations 
Examine the Hydrology Study Site for materials 
in soil, rocks, and vegetation that influence the 
pH of the water. 
Try to identify and quantify influences that are 
not always present at the study site, such as 
precipitation or some event upstream of your 
sampling site. See if the pH of your site changes 
over the course of a day. Photosynthesis can 
cause fluctuation in pH (although these will be 
too small to be measure with most pH paper)
Student Assessment 
After the game sit with students around the results 
board and identify what samples they have found, 
where the samples were found, and the pH of the 
samples. Encourage students to present their own 
ideas about why different samples have different 
pH values. Emphasize differences among water 
samples from soils, rocks, artificial surfaces, 
lakes, rivers, etc. Mention the acid neutralization 
capacities (alkalinity) of some rocks and the acidic 
influences of different materials. Ask them why it 
was difficult to find samples for some pH levels 
and easy to find others. 
Acknowledgments 
The pH game was created and tested by the 
leaders team of TEREZA, the Association for 
Environmental Education, Czech Republic
. 


pH Game

http://www.globe.gov/tctg/hydro_la_phgame.pdf?sectionId=162

pH Game

Abstract

Similar works

Full text

Available Versions

Digital Library for Earth System Education