Topic: Sugars – sucrose

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Primary school. Chemistry.

X. Biologically relevant chemicals. Student:

9) gives the molecular formula of sucrose; tests and describes the selected physical properties of sucrose; indicates its uses.

General aim of education

The student discusses the structure, properties and use of sucrose.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• what is the molecular formula of sucrose;

• investigate and describe the properties and use of sucrose;

• write down the equation of sucrose reaction with water.

Methods/techniques

• expository

  • talk.

• activating

  • discussion;

  • brainstorming;

  • mind map.

• 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 asks students to collect information on sucrose in the form of a mind map. Students present their suggestions during a brainstorming session, and the moderator writes them on the board. After the creative phase, students verify ideas and the teacher supplements the information if necessary.

2. The teacher asks students to write down the total sucrose pattern on the pages. Then he displays the structural formula and model of the sucrose molecule and initiates discussions about its construction (if necessary, asks auxiliary questions). Then he asks one of the students to summarize the discussion. Students verify previously written formulas with the ones displayed on the board.

3. The lecturer refers students to the abstract and asks you to read the description and instructions for carrying out the experiment examining the physical properties of sucrose. It divides students into exercise groups. Then he asks for the execution of experience 1 and recording the observations and conclusions in the form in an abstract..

4. The teacher announces a movie. He instructs his pupils 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. The teacher points the person who shares his insights and explains the reasonableness of the conclusions noted.

5. The teacher divides the students into groups. He explains that their task will be to find out information about the use of sucrose. Students can use all available sources. Then the group leaders present the effects of their work.

6. The teacher asks the students to review the sugar content presentation in several foods. He initiates discussions on the excessive amount of sugar consumed every day, and then on performing an interactive exercise – inserting the text in the picture.

7. Students, working individually or in pairs, carry out interactive exercises to check and consolidate knowledge learned during the lesson. Selected people discuss the correct solutions for interactive exercises. The teacher completes or straightens the statements of the proteges.

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.

2. Make at home a note from the lesson using the sketchnoting method.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Sugars – sucrose

This sugar, which we use every day e.g. for sweetening tea, was already known in ancient times. It was obtained on an industrial scale from sugarcanes in the Middle East. It was brought to Europe by the Greeks in the 4th century BC. – at that time it was used as a medication. Deliveries to Europe increased significantly when America was discovered because sugarcane plantations were established there. In the mid‑18th century people started to obtain sugar from sugar beets. In Poland the first sugar factory was built in 1802 in Lower Silesia.

Sucrose is one of the disaccharides and has the following formula: CIndeks dolny 12₁₂HIndeks dolny 22₂₂OIndeks dolny 11₁₁. The sucrose molecule is composed of fragments of two simple sugars: glucose and fructose.

Are the properties of sucrose similar to those of glucose?

Each of you can make candies called caramels. Just pour a few spoonfuls of sugar into a saucepan and keep it over low heat. As a result of heating, caramel is created, which should be poured into a bowl and allowed to cool down. Candy is ready!

In the human body, during digestion, sucrose is broken down into simple sugars. The following are necessary for this reaction: enzymes, water and the hydrochloric acid found in the digestive tract. This process is called hydrolysis.
${\text{C}}_{\text{12}}{\text{H}}_{\text{22}}{\text{O}}_{\text{11}}\text{ + }{\text{H}}_{\text{2}}\text{O}\stackrel{\text{enzymes, HCl}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}\text{ + }{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$$\text{sucrose + water} \stackrel{\text{enzymes, HCl}}{\to }\text{ glucose + fructose}$
The initial digestion of sucrose may begin already in the oral cavity under the influence of the enzyme – salivary amylase – present in the saliva. Therefore, sugar does not even need to be swallowed. Just put a small amount of it in your mouth and wait until saliva decomposes it into simple sugars. They will be absorbed by the epithelium of the oral cavity's mucous membrane.

The bulbs of sugar beets and stems of sugarcanes are the main sources of sucrose. In small quantities, it may also be present in some fruit and vegetables.

Owing to its properties, sucrose has been used in many sectors of industry.

It is a well known fact that excessive amounts of sweets can lead to obesity. But is this the only effect? Excessive amount of sugars in our body is not recommended because it can cause many health issues, such as:

• damage to the immune system,

• disturbance of the mineral balance in the body,

• increase in glucose and insulin levels,

• vision impairment,

• spoilage of teeth,

• heart diseases,

• raised cholesterol levels,

• diabetes, and many others.

Excessive consumption of sugar has a negative effect on the brain tissue. Children and adolescents eating large amounts of sugar do not control their emotions, are nervous and aggressive. Sugar can also cause depression, irritation and fatigue. What's important, sugar can be addictive, much like nicotine and alcohol.

• Sucrose is a disaccharide with the following formula: CIndeks dolny 12₁₂HIndeks dolny 22₂₂OIndeks dolny 11₁₁. It is a white, crystalline substance and has a sweet taste. It dissolves well in water.

• Sucrose has no reducing properties and does not give a positive Trommer's test result.

• In the human body, sucrose undergoes hydrolysis under the influence of enzymes and the hydrochloric acid – it decomposes into glucose and fructose.

• Sucrose is present in sugar beets and sugarcanes. In smaller quantities, it may also be found in fruit and vegetables.