Content Library

Heat

Heat

Activity 1

Take a rod or flat strip of a metal, say of aluminium or iron. Fix a few small wax pieces on the rod. These pieces should be at nearly equal distances. Clamp the rod to a stand. If you do not find a stand, you can put one end of the rod in between bricks. Now, heat the other end of the rod and observe.

Which point will begin to melt first? Give your reasons.

Activity 2:

Heat water in a small pan or a beaker. Collect some articles such as a steel spoon, plastic scale, pencil and divider. Dip one end of each of these articles in hot water. Wait for a few minutes. Touch the other end. Enter your observation. Give reasons for your answer.

Article Material with which the article is made of Does the other end get hot Yes/No
Nutrition in Plants

Nutrition in Plants

Activity 1.1

Activity 1.1 asks us to put a plant in the dark for 72 hours, test its leaf for the presence of the starch with iodine and compare the result with a plant kept in sunlight.

How do we do a test for the starch

We first put the leaf in a boiling solution of spirit. Spirit breaks the leaf cells, and all the green colour of chlorophyll goes into the spirt. We do this because the colourless leaf is easy to stain with iodine. Now we put iodine solution on the colourless leaf. If the leaf contains the starch, it turns blue.

Science Class 7 Chapter 1 Activity 1.1
Leaf of the plant kept in sunlight turn blue with iodine.

Observation:

Leaf of the plant kept in the dark does not turn blue. While the leaf of the plant remained in sunlight turns blue with iodine.

Inference/conclusion:

This experiment shows that the plant kept in the dark does not produce starch. Thus we can say that sunlight is essential for starch formation.

Explanation:

Plant prepare their food from the carbon dioxide and water in the presence of the sunlight. When we keep the plant in the dark, a plant is not able to make their food. As a result, when we put the iodine solution to that leaf, it does not turn blue. A plant kept in sunlight can make their food, so the iodine solution turns blue.

NCERT Class 7 Chapter 1 Activity 1.2 explanation
Thin threads of bread mould
Activity 1.2

Activity 1.2 asks us to water a piece of bread, put it into a warm place and observe it.

Observation: Green and black cotton thread like mould appear on the bread.

Explanation:
Activity 8.2 How do Organisms Reproduce explanation
Bread mould with spores under the microscope

The wet and warm place is the favourites of saprophytes. Saprophytes are the organism which obtains their nutrition from dead or decaying materials. They clean the dead materials, so they are also called ‘scavengers of the earth’. Their spores are present everywhere in the air. They settle at a damp and warm place and multiply. Bread mould is favourite of a fungus named Rhizopus. So, we also call them Bread Mould. They are a thin thread-like structure with a bulb. Bulb stores the spore, which on maturation released into the air.

https://studdy.in/ncert-class-7-chapter-1-activity-1-1-1-2-explanation/

Concept of Subtraction- some strategies

Concept of Subtraction- some strategies

Strategy 1: Using Manipulatives or objects

Step 1: Take some colored buttons ( 20 buttons) on a check board.

Step 2: Speak aloud  that you are taking away 5 buttons from the 20 kept on the check board.

Step 3: Ask children to do back ward counting starting from 20 and reach the number which is left after removing 5 buttons.

You can apply this technique by calling every child in the class or make groups of 2 and give each group buttons or cards made of chart paper to do this activity.

Strategy 2: Count Back

Step 1: You can use a colored chalk for this.

Write a two digit number( ex 12) on the board and ask students to remove the number from it (ex 3)

                 12  ◊   ◊   ◊

                                                                                                 11  10  9

equation will be= 12 -3= 9

put the bigger number in your head and draw dots to help you count back and find the difference

Strategy 3: Visualize when solving word problems

Step 1: Ask students to visualize what is given in the word problem. for eaxmple :

Meera had 8 candies. She gave 3 candies to her friend. How many was she left with?

Step1: Meera= Ο Ο Ο Ο Ο Ο Ο Ο

Step 2: She GAVE= Ο Ο Ο

Step 3: Meera was left with=

equation: 8-3=

Refer to the site for more clarity: https://susanjonesteaching.com/subtraction-activities-first-grade/