ODS View Scenario/Lesson Plan Summary Page

Learning Scenario
Acids, bases and environment
Last updated 17/07/2014, by Miguel Neta
Domain: alkalis and bases, Science>Chemistry>Chemical Reactions>Acids
Learning objectivesCognitive - Knowledge:
Factual: Learn the pH scale.
Conceptual: Understand the concept of acid and base. Understand consequences of pollution at long terms.
Procedural: Improve experimental skills.
Cognitive - Process:
To remember: pH scale.
To understand: Acids and bases. Acid-base indicator.
To apply: Experimental activities.
To perform confidentially following instructions
Grade & Age13 to 15 years old.
Grade: school education
Keywords/subjectacid base pH laboratory security acidification
Prerequisites The students need to understand what is a chemical reaction. They will need some experimental skills and knowledge of basic laboratorial materials.
Difficulty Leveleasy
Author(s)Name: Miguel Neta Organization: Agrupamento de Escolas Dra Laura Ayres Role: Physics and Chemistry teacher
Description/ main idea
šThe teacher introduces the subject of acids, bases and the pH scale; 
šThe students, with their parents help, analyze some materials at home to compare their acidity or basicity using a homemade pH indicator;
Students observe the relation between human behavior (polution) and ocean acidity.
Final presentation of some of the parents-students works.

pH scale

Demonstrative activity of the pH scale.

Multimedia materials will be used to explain the modification of the acid-base indicator color.

pH and Color Change


"Students will see a demonstration of a color change using universal pH indicator. Students will see an animation showing that water molecules interact and separate into the H3O+ ion and the OH ion. Students will see that the pH of a solution is related to the concentration of these ions in water."

Lesson plan available at: http://www.middleschoolchemistry.com/lessonplans/chapter6/lesson8

(The American Chemistry Society lesson plan should be adapted to be an demonstrative activity.)


Educational objects (as url):
1. pH and Color Change
2. Related multimedia


50 Minutes

Good Laboratory Practice video

The students needs ot be prepared to use some laboratorial material with security.

A video should be seen by students with their parents, at home, before the next phase.

Good Laboratory Practice


Video about good laboratory practice:


Educational objects (as url):
1. Good Laboratory Practice Video


10 Minutes

Homemade pH indicator

Students and their parents will be able to make a homemade pH indicator and use it to control the acidity/basicity of some daily use materials.

They should be instructed by the teacher to make pictures of their work for a presentation to others parents and students.

Red cabbage indicator


The students will work with their parents to make a pH indicator and then use it to see the kind of solutions they use at home (acids, bases or neutral).

The procedure is available at: http://chemistry.about.com/od/acidsbase1/a/red-cabbage-ph-indicator.htm

and a video at: http://video.about.com/chemistry/Cabbage-pH-Indicator.htm

Students and parents should take pictures of their work so they can present it later.

(Some laboratory material will be replaced with home materials... beakers for glass cups, for example.) 


2 Hours

Experimental pH indicator activity

The students will use the 'Heureka Colourful Chemistry' (www.xplora.org) to make experimental use of pH indicator in laboratory materials/solutions.

Heureka Colourful Chemistry


Use (after adapte for a specific class and the materials of each school) the lesson plan available at: http://www.xplora.org/shared/data/pdf/chemistry_colour.pdf

Students should take photos during their work to present it later.


1 Hours & 3 Minutes

Water acidification

After students understand the use of pH indicatores to test solutions they will observe the consequence of the solubility of CO2 in water.

Acidification of water


Students will observa the acidification of water by the presence of CO2.

The lesson plan 'Carbon dioxice can make water acid' is available at: http://www.middleschoolchemistry.com/lessonplans/chapter6/lesson10

Students can understand the reaction


Educational objects (as file):
1. CO2 reaction with water


50 Hours

Polution and ocean acidification


Students are asked to think about relation with previous activity and human behavior (polution) and ocean acidity.

This task is made in small grups for later presentation.

Final presentation

Parents are invited to present the work that they have done with their children at home at a non formal reunion.

A group of small students present a report about how human polution is changing ocean water pH and consequences of that change.

Teacher, parents and students can change ideas during a brief informal meeting (drinks and snacks are a good idea!).



Students and parents use the pictures that they have taken to make a brief presentation about how their work at home.

Each group organise the tested materials in grups (strong acids, weak acids, neutral solutions...).

They talk about difficulties that they have encontered.