Topic: Water and its properties – solution components and testing of substances’ solubility

Target group

Elementary school student (grades 7. and 8.)

Core curriculum

Elementary school. Chemistry.

V. Water and aqueous solutions. Pupil:

2) give examples of substances that do not dissolve in water, and examples of substances that dissolve in water, forming solutions; gives examples of substances that form colloids and suspensions with water;
3) designs and conducts experiments on the solubility of various substances in water.

General aim of education

The student designs and conducts experiments on the solubility of various substances in water

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• specify, for example, a solvent and a solute;

• give examples of substances that dissolve in water and those that do not dissolve in water;

• carry out an experiment, the purpose of which is to investigate whether a substance dissolves in water or not.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• exposing

  • film.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

3. Health and safety – before starting the experiments, students familiarise themselves with the safety data sheets of the substances that will be used during the lesson. The teacher points out the need to be careful when working with them.

Realization

1. The teacher introduces the students to the issue implemented during the lesson. He asks the class participants to read the experiment's instructions in the abstract (experiment 1: “Dissolving sugar in water”). The teacher divides students into groups, distributes work cards and appropriate equipment, glass and reagents to perform the experiment. Students follow the instructions. They record the conclusions in the form. The teacher initiates a discussion in relation to the observations noted.

2. Volunteers summarize the discussion and explain in their own words the meaning of the concepts: solvent and solutes.

3. The teacher announces a movie titled “Testing the solubility of various substances in water”. He instructs his students to write a research question and a hypothesis in the form provided in the abstract. Then he plays the video and the students note their observations and conclusions. Selected people present the results of their work.

4. Students, working in pairs, write examples of substances that dissolve in water and those that do not dissolve in water. The indicated couples present their examples on the class forum.

5. Students carry out the interactive exercises checking the level of knowledge learned during the lesson. The teacher initiates a discussion during which the correct solutions for all the exercises performed by the students are discussed.

Summary

1. Teacher asks: If there was going to be a test on the material we have covered today, what questions do you think would you have to answer? If the students do not manage to name all the most important questions, the teacher may complement their suggestions.

Homework

1. Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Water and its properties – solution components and testing of substances’ solubility

All solutions are made up of the following components: solvent and solutes.

Different substances vary in terms of solubility in water. Some dissolve in water very well and form a true solution, for example sodium chloride or sucrose (the main ingredient of sugar). There are also substances that dissolve in water not that well and form suspensions, e.g.: potato starch, silica (sand), chalk. When trying to dissolve egg white in water, we will end with a colloidal solution.

• All solutions are made up of a solvent and a solute.

• In a solution the quantity of solvent is greater than the quantity of solute.

• Substances differ in terms of their solubility in water.