**Teacher’s Guide:**

- Divide students into groups;
- Conduct a brief instruction on working with scissors and cardboard products;

**Goals:**

- To get acquainted with the concept of “scales”, with the role of scales in human life;
- Familiarize yourself with the methods of weighing objects;
- Develop logical thinking.

Read the safety instructions before you start **[ safety insructions ]**

**Introduction**

**A scale** is a device for weighing and determining the weight (mass) of bodies.

People started using scales many thousands of years ago. People in those days used primitive devices to determine the weight of objects. Scales were necessary for people to trade. They have also been used to identify real and fake gems [1].

In ancient times, the weight of an object was compared with the weight of seeds of common plants, stones and grains. In this way, people determined the weight of an object.

The next step in weight units was taken in Ancient Babylon: people have already begun to introduce standard units for measuring weight such as mina, shekel, talent. These measurements later came to the Israelites, Greeks and Romans. Despite the similar names of weight units, the weights of the same units could differ in different states. The names of units of weight could change and have different meanings until people came to more generally accepted measures of measurement [2].

**References:**

[2] https://www.convert–me.com/ru/history_of_measurement_faq.html

**Practical part**

- Download and print layouts [ download].
- Cut out the details.

Using the small rectangle as a template, cut out 6 rectangles from the cardboard.

Glue 3 small rectangles to each other using paper glue

Cut out 2 triangular shapes

- Cut out one large rectangle
- Measure the length and width of the large rectangle
- Divide the length and width into 2 parts and draw a middle line

- Glue the small rectangle to the middle of the large rectangle as shown in the picture below (place the small rectangle in a vertical position)
- Fix the small rectangle by gluing pieces of triangular-shaped cardboard on both sides.

Measure the width of the small rectangle and mark the middle with a simple pencil at the top.

Measure the length and width of the second small rectangle and mark the middle with a pencil

Make a hole using the pen in the middle of the rectangles (areas shown in the picture below)

- Using a cover of paper glue (or any other round object with an identical size) draw 2 circles on the cardboard and cut them out
- Make holes in the middle of the circles with a pen

Break off a 4 cm piece from a wooden skewer

- Attach two small rectangles to each other with the resulting piece of wooden skewer.
- Put cardboard circles on top of the skewer and glue them using thermoplastic glue (only the teacher uses thermoplastic glue)

- At the two ends of the small rectangle, make holes in the middle with a pen.
- Make cuts in the top line (areas shown in the picture below)

- Cut out two squares of cardboard with a side equal to 9 cm
- Step back 1 cm from the edges of the square and draw lines with a pencil

Make holes using the handles at the intersections of the line.

- Cut 4 pieces of rope measuring 25 cm
- Pass the ropes through the holes of the squares and connect the ends as shown in the picture below.

Put the received parts on the base

Cut pieces out of 4cm juice tubes

Fill the pieces of tubes with plasticine

*Next, the students play a game to determine the weight of objects. Have the students measure the weight of the candies (small toys) using the filled weighing tubes. One filled tube will be considered as 1 kg of weight (units of measurement can be changed).*

Place the objects whose weight you want to measure in one direction, and put the filled tubes in the other. Count the number of filled tubes at the moment when both sides of the balance are equal. The weight of the object will be equal to the number of tubes on the scales at the moment of equalization of the two sides of the scales.

*Have the students improve the layout of the scale with colored cardstock and colored pencils.*

**Conclusion**

On this project, the students got acquainted with the device and the principle of operation of the scales by constructing their own scale model. It is recommended that you think about improving the scale layout design.

**Evaluation**

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