Math 2 Lesson: Millimeters
1.1. Knowledge to remember
– Units of length in millimeters, the symbol and magnitude of millimeters, the relationship of millimeters to centimeters and meters.
– Add and subtract operations with millimeters and related puzzles.
1.2. Math forms
Form 1: Converting units of measurement
I remember how to convert the units: 1cm = 10mm, 1m = 1000mm.
Form 2: Perform addition and subtraction with units of length millimeters
For numbers with the same unit of measure, add or subtract the numbers and keep the unit of measure in the result.
Form 3: Find the perimeter of a triangle
To find the perimeter of a triangle, you need to find the sum of the lengths of the sides of the triangle. (Same unit of measure)
1.3. Solving Textbook Exercises page 153
1cm = …mm 1000mm = …m 5cm = …mm
1m = …mm 10mm = …cm 3cm = …mm
Apply the knowledge you have learned about units of measurement and then fill in the blanks with the appropriate number.
1cm = 10mm; 1m = 1000mm.
1cm = 10mm 1000mm = 1m 5cm = 50mm
1m = 1000mm 10mm = 1cm 3cm = 30mm
How many millimeters is each of the following lines?
Read the lengths of the measured lines.
Attention: 1cm = 10mm.
The straight line MN is 60mm long.
Line segment AB is 30mm long.
The CD straight segment is 70mm long.
24mm, 16mm and 28mm.
The perimeter of a triangle is equal to the sum of the lengths of its sides (in the same units).
The perimeter of the triangle is:
24 + 16 + 28 = 68 (mm)
a) The thickness of the book “Math 2” is about 10…
b) The thickness of the flat ruler is 2…
c) The length of the ballpoint pen is 15…
Enter the appropriate length unit when measuring the thickness or length of objects.
a) The thickness of the book “Math 2” is about 10mm.
b) The thickness of the flat ruler is 2mm.
c) The length of the ballpoint pen is 15cm.
Attention when solving: The thickness of common objects is measured in millimeters.
1.4. Solving Textbook Exercises page 154
13m + 15m = 5km x 2 =
66km – 24km = 18m : 3 =
23mm + 42mm = 25mm : 5 =
Perform the calculation with the numbers and then write the length unit in the result you just found.
13m + 15m = 28m 5km x 2 = 10km
66km – 24km = 42km 18m : 3 = 6m
23mm + 42mm = 65mm 25mm : 5 = 5mm
A person travels 18km to the town, then another 12km to the city. How many kilometers did he travel in all?
To calculate how many kilometers that person has traveled, we calculate the sum of the lengths of the two given distances.
The distance traveled by the person is:
18 + 12 = 30 (km)
Answer: 30 km.
Choose a letter that has a right answer:
A tailor uses 15m of fabric to sew 5 sets of the same clothes. How many meters of fabric are needed to make such a garment?
To find the solution, we divide the number of meters of fabric by the number of clothes.
We have: 15 : 5 = 3 (m)
Circle the letter C.
Measure the lengths of the sides of triangle ABC and then calculate the perimeter of that triangle.
Use a straightedge with centimeter divisions to measure the lengths of the sides of the triangle.
– The perimeter of a triangle is equal to the sum of the lengths of its three sides (calculated in the same units).
Measure the lengths of the sides of triangle ABC, we get:
AB = 3cm, AC = 4cm, BC = 5cm.
The perimeter of triangle ABC is:
3 + 4 + 5 = 12 (cm)