Science (EVS K-5) · Class 7 · Fibre to Fabric · Term 3

Varieties of Silk

Discover the different types of silk, such as Tussar, Eri, and Muga silk, produced by various species of silk moths, and learn about their unique characteristics.

TL;DR:Move beyond the common Mulberry silkworm and introduce your students to the fascinating world of India's other silk superstars!

• CBSE Learning Outcomes
• NCERT Class 7 Science: Chapter 3 - Fibre to Fabric

About This Topic

This topic, 'Varieties of Silk', is an essential extension of the Class 7 Science chapter 'Fibre to Fabric', as per the NCERT framework. While the core curriculum focuses heavily on Mulberry silk, this deep dive introduces students to the rich diversity of sericulture in India, a global leader in silk production. It explores non-mulberry silks like Tussar, Eri, and Muga, which are integral to the cultural and economic fabric of various Indian states, particularly in the North-East and eastern parts of the country.

By examining these different varieties, students move beyond a monolithic understanding of silk. They learn that the properties of a fibre are directly linked to the specific species of moth and its diet. This topic provides a perfect opportunity to integrate concepts from biology (insect life cycles, biodiversity), geography (regional industries), and social sciences (cultural heritage, rural economy). The goal is to foster an appreciation for India's unique biodiversity and the traditional knowledge systems that have sustained these unique forms of silk production for centuries.

Key Questions

1. Identify three different types of silk and the moths that produce them.
2. Compare the texture and lustre of Muga silk with Mulberry silk.
3. Explain why different types of silk have different properties.

Learning Objectives

• Identify Tussar, Eri, and Muga as three distinct varieties of Indian silk.
• Name the specific silk moths and their primary food plants for each variety of silk.
• Compare the physical properties, such as texture, lustre, and colour, of Mulberry silk with at least two other types.
• Explain how the species of the moth and its diet determine the characteristics of the silk produced.
• Locate on a map of India the primary regions associated with the production of different silks.

Key Vocabulary

Sericulture	The process of cultivating silkworms and harvesting their cocoons to produce silk.
Tussar Silk	A type of wild silk produced by moths that feed on the leaves of Arjun and Asan trees, known for its rich texture and natural deep gold colour.
Eri Silk	Also known as 'Ahimsa silk', this is a fine, dense silk with a woolly feel, produced by silkworms that feed on castor leaves. The moth is allowed to emerge from the cocoon.
Muga Silk	A rare and durable silk from Assam, known for its natural, shimmering golden-yellow hue. It is produced by the semi-domesticated *Antheraea assamensis* silkworm.
Lustre	The natural sheen or gentle glow of a fibre's surface, which is a key characteristic used to identify different types of silk.

Watch Out for These Misconceptions

Common Misconception

All silk comes from one type of silkworm that only eats mulberry leaves.

What to Teach Instead

Mulberry silk, from the *Bombyx mori* moth, is the most common, but it is just one type. Other moths, often called 'wild' silk moths, produce different silks like Tussar (from moths feeding on Arjun trees) and Eri (from moths feeding on castor plants).

Common Misconception

Silk is always very smooth and shiny.

What to Teach Instead

The texture and lustre of silk vary greatly. While Mulberry silk is known for its smoothness and sheen, Tussar silk is coarser with a copper-coloured sheen, and Eri silk has a more cotton-like, less lustrous finish.

Common Misconception

Silkworms are a type of worm.

What to Teach Instead

The term 'silkworm' is a common name, but scientifically, it is not a worm. It is the larval stage, or caterpillar, of a silk moth.

Active Learning Ideas

Mystery Object

Silk Swatch Investigation

Provide students with small, labelled fabric samples of Mulberry, Tussar, Eri, and Muga silk. Students observe them with a magnifying glass and record their observations on texture, lustre, colour, and thread thickness in a comparison table.

25 min·Small Groups

Mystery Object

Map the Silks of India

Give students an outline map of India. They research and mark the primary states where each type of silk (Tussar, Eri, Muga, Mulberry) is produced, creating a visual guide to India's sericulture landscape.

30 min·Pairs

Mystery Object

Moth-to-Fabric Match-Up

Create a set of cards with pictures of different silk moths (*Bombyx mori*, *Antheraea assamensis*, etc.) and another set with pictures or descriptions of the silk they produce. Students work in groups to correctly match the moth to its silk.

15 min·Small Groups

Real-World Connections

• The use of specific silks in traditional Indian garments, such as the Muga silk Mekhela Chador in Assam or Tussar silk sarees from Jharkhand and Bihar.
• The economic importance of sericulture as a source of livelihood for many rural and tribal communities across India.
• The concept of 'Ahimsa silk' (Eri silk) connecting to ethical and sustainable fashion choices.
• The Geographical Indication (GI) tag given to unique Indian silks like Muga silk to protect their origin and quality.
• The use of silk fibres in non-textile applications, such as in the medical field for making absorbable surgical sutures.

Assessment Ideas

Discussion Prompt

Conduct a 'Think-Pair-Share' where students are asked to compare Muga and Mulberry silk. Listen to their discussions to gauge understanding of key differences.

Peer Assessment

Students create a small presentation or a fact file on one non-mulberry silk variety, covering the moth, its habitat, the silk's properties, and its main uses.

Quick Check

Provide a checklist where students can rate their ability to identify three types of silk, name their source moths, and describe one unique feature of each.

Frequently Asked Questions

Why is Muga silk, the golden silk of Assam, so expensive?

Muga silk is one of the rarest silks in the world. It is produced by a moth that is semi-domesticated and native only to Assam. The process is labour-intensive, and the silk's natural golden lustre, which actually improves with age, and its high durability make it highly prized and costly.

What is 'Ahimsa silk' or 'Peace silk'?

This usually refers to Eri silk. The cocoon of the Eri silkworm has an opening at one end, so the moth can emerge unharmed before the cocoon is processed. This non-violent method of harvesting silk makes it popular among those who wish to avoid harming living creatures, like followers of Buddhism and Jainism.

Do different silks need different care when washing?

Yes. Generally, all silks are delicate and should be hand-washed or dry-cleaned. However, Muga silk is known to be very durable, while others might be more sensitive to harsh detergents. It's always best to follow the care instructions for the specific type of silk fabric.