Chemistry lesson scenario

Lesson plan elaborated by: Krzysztof Błaszczak

Target group:

Elementary school student (grades 7 and 8)

Core curriculum:

Primary school. Chemistry.

I. Substances and their properties. Student:

10) carries out calculations using the terms: mass, density and volume.

Abstract title:

1.5.The role of the density of substances and their mixtures in everyday life

Link to lesson:

https://www.epodreczniki.pl/reader/c/153030/v/43/t/student‑canon/m/m1fd73e065fee3267

Topic: Density of substances

Time: 45 min

Aim of the lesson:

Student carries out calculations using the terms: mass, density and volume

Criteria for success:

• you will explain why the density of solids is greater than the density of gases on the basis of the internal structure

• you will carry out calculations using the terms: mass, density and volume

Key competences:

• communicating in the mother tongue

• communicating in foreign languages

• mathematical competences and basic scientific and technical competences

• IT competences

• learning to learn

Acquired and improved skills:

• using the digital textbook

• communication

• computer literacy

• research and investigation

• creative thinking and acting

• cooperation

• conducting experiments

Teaching aids:

• computers with speakers and internet access

• multimedia resources contained in the abstract and e‑textbook

• multimedia projector

• interactive whiteboard / blackboard and chalk

• Methodology Guide or green, yellow and red sheets of paper

• equipment, laboratory glassware and reagents for the experiment - see description of 1st and 2nd experiment in the abstract and in the methodical commentary

Methods / techniques:

• problematic: directed conversation, didactic discussion

• exposing: the film

• programmed: using the computer, using an e‑textbook

• practical: experiment – teacher demonstration

• giving: elements of the lecture

• stoplight technique for student self‑assessment, and thus determining the level of mastery of the discussed issue on an ongoing basis

Forms of work:

• collective activity

• individual activity

Lesson plan overview:

Introduction

3. 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 stoplight technique. He presents the aims of the lesson on a multimedia presentation in the student's language 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).

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

5. Health and safety - before experiments, the teacher familiarise students with the characteristics of the substances to be used during the lesson. He indicates the need to be careful when handling them.

Realization

6. The teacher emphasizes the fact that we examine the density of the substance every day by referring to various examples from the environment: sweetening tea, pouring salt into the soup, putting potatoes, carrots, spices and other ingredients to the soup, etc. Some substances fall to the bottom of the pot, others float on the surface of the liquid. Some everyday items, such as a Styrofoam coffee cup or aluminium rims, are referred to as light, and others, such as steel rims or leaded apron covering the patient from radiation, as heavy. One kilogram of one substance has the same mass as one kilogram of another, however these substances may have different volumes. Their density differs. Why is this happening? Which has a higher density: a body that has a larger mass at the same volume, or a body that has a larger volume with the same mass. The implementation of the content of this topic will allow you to answer these questions.

7. The teacher refers students to the abstract and asks for familiarization with the content of „What is mass?” section - he starts the discussion by raising example issues:

• how can you define the mass?

• in which units of the SI system the mass is expressed

• what is the result of the analysis of the table „Prefixes in the SI system”

• whether Styrofoam balls of comparable volume have a similar mass

• whether weight and mass mean the same thing

• what determines the weight

• what will be the weight of each student on Jupiter and what will be on Mars?

8. The teacher refers students to the abstract and asks for familiarization with the content of „What is volume?” section - he starts the discussion again:

• how can you define the volume?

• in which units of the SI system the volume is expressed and which unit is generally used in everyday life

• what determines the methods of determining the volume

• what is the result of analysis of the table „Units of volume”

• how the volume of liquid is determined

• how the volume of gases is determined

• how the volume of solid substances with regular shapes is determined.

9. The teacher asks the students the question: „How is the volume of solids with irregular shapes determined?” – volunteers answers the question and then the teacher conducts an experiment according to the instructions described in the methodical commentary.

10. The teacher introduces the concepts of parallax, lower and upper meniscus in relation to results readings.

11. The teacher refers students to the abstract and asks for familiarization with the content of „What is density?” section - he starts the discussion regarding the task under the definition of density.

12. The teacher writes the question down on the board: „How is the density calculated?” – then he notes the formula for the density of substances with units down; he explains the meaning of symbols and explains what determines the density of a substance. He analyses the task to compare the density of a substance with the density of water.

13. The teacher hands out worksheets and then displays a movie from the „Water Rainbow” abstract on the interactive whiteboard. Before the movie, students formulate and write a research question in the worksheets. During the screening they should observe the changes, then discuss them in class, draw conclusions and also write them down in the worksheets. The teacher asks the students: „What happens if you use sugar instead of salt in the experiment? What happens if you dip the straw in solutions in a different order? „

14. The teacher displays a movie from the „Drink Density” abstract on the interactive whiteboard. Students - as before - formulate a research question and hypotheses, note them down in the worksheets. They observe changes in the experiment, draw conclusions and write them down in the worksheets.

15. The teacher asks students to perform interactive exercises in abstract.

Summary

16. In the summary of the lesson, the teacher asks students to expand following sentences:

• I got to know that…

• It was easy for me ...

• It was difficult for me…

He can use an interactive whiteboard in abstract or instruct students to work on it.

Multimedia:

I. Interactive exercise - single choice

II. Movies “Water Rainbow” and “Drink Density”

III. Logs for notes and observations made during the experiments

IV. Interactive whiteboard for lesson evaluation and self‑assessment of the student's knowledge

Methodical commentary:

Teachers demonstration „Determining the volume of solids with irregular shapes”

List of required materials/teaching aids

Equipment and laboratory glassware: beaker, measuring cylinder, optional - ring, screw, metal ball or another object

Reagents: water

Hot to conduct the experiment

17. Pour 10 cm3 of water into measuring cylinder.

18. Read the volume of water and note the result down.

19. Insert the object which volume will be examined.

20. Read the volume of water with the test item and note the result down.

21. Subtract both readings, the subtraction result is information about the volume of the subject being examined.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Density of substances and their mixtures in everyday life: mass and volume

One of the task during the strongman competition is to lift a stone or concrete ball (weighing 110 - 190 kg) from the ground and place it on the platform in the shortest possible time. Do balls of comparable volume made of Styrofoam have a similar mass?

Matter is everything that surrounds us which has a mass and a specific volume.

The formal definition is:

The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015 × 10Indeks górny −34⁻³⁴ when expressed in the unit J⋅s, which is equal to kg⋅mIndeks górny 2²⋅sIndeks górny −1⁻¹, where the metre and the second are defined in terms of c and ΔνIndeks dolny Cs_Cs.

*SI (Système international d'unités) – International System of Units is a system of physical units, such as, for example metre, kilogram, second, and multiples thereof determined using prefixes.

The body with the same mass – depending on the force of gravity and the place of measurement – may have different weight. The gravity on the Moon is lower than on Earth, so the astronaut’s weight is lower on the Moon. The unit of weight (force of gravity) is Newton (N).

Volume determines how much of space is occupied by a given body; the unit of volume is a cubic meter (mIndeks dolny 3₃) in SI

In everyday life, we usually use a smaller unit – litre (1 dmIndeks górny 3³ = 1 litre). Liter is not a unit of the SI system. The methods for determining the volume of a substance depend on its state of matter. Volume of liquid is measured using laboratory glassware with graduation scale. In the laboratory, measuring cylinders and pipettes are used for this purpose, and cubic decimetre (dmIndeks dolny 3₃) is a unit. At home, we can use glasses or spoons. The following are examples of approximate volume conversion rates.

The volume of gases depends on the size of their „packaging” because the gases fill up all of their available space. For example, when drinking water from a bottle, the air takes up the empty space. The empty 1 litre bottle contains a litre of air.

The volume of solids with regular shapes can be calculated based on their dimensions.
The volume of cube is calculated using the formula:
$V=a^3$, and the volume of cuboid – using the formula: $V=a·b·c$

Volume of solids with irregular shape can be determined by immersing an object in a cylinder filled with water. The volume is a difference between the final volume (after immersing the object) and the initial volume of water in the cylinder.

Meniscus
Meniscus is the curve (place of adhesion) in the upper surface of a liquid close to the surface of the object – measuring cylinder. There is convex (water) and concave (mercury) meniscus – it depends on the value of adhesive forces between liquid molecules and glassware walls as well as on the intermolecular forces between liquid molecules.

Parallax is the phenomenon of erroneous reading of the measuring instrument. The reason is the wrong angle at which the person is looking. The line of sight passing through the indicating element, e.g. the liquid bar in the measuring cylinder, is directed to the wrong point on the reading scale behind this element. The difference between the actual reading and the correct reading value is called the parallax error.

• Mass is a measure of the amount of matter determined by means of a weight.

• The kilogram pattern is stored at the International Bureau of Weights and Measures in Sѐvres near Paris.

• The body of the same mass, depending on the strength of gravity and the place of measurement, may have different weights.

• In the SI system, the unit of volume is cubic meter mIndeks dolny 3₃.

• The methods for determining the volume of a substance depend on its physical state.

• The volume of the irregularly shaped solid can be determined by immersing this object in a cylinder with water.

volume, weight, mass, meniscus, substance