Working With LengthsViki, Janina, Uli, Celina und Corbi

Friday, 13th of March 2015

Contents

• Introduction: Learning Objectives Uli

• Main 1: Adding, Subtracting, Multiplying and Dividing with Lengths Viki

• Main 2:Perimeters Janina

• Main 3:Word Problems Celina

• Review: Lessons learned Corbi

Working with lengths

Main 1: Addition and Subtraction

We will talk about working with lengths! Maybe you already know what I am going to „teach“ you but lets start…

•First of all you need to convert e.g. cmm

•No matter which calculation you have to do: Do it with the same unit!

•Then you just need to add and/or subtract like you do with normal numbers

Main 1: Multiplication and Division

Now, multiplying and dividing is almost the same:

•Convert e.g. m km

•Then just multiply and / or divide like you do with normal numbers!

I hope now you know how to do the four operations with lengths!

Main 1: Addition and Subtraction

A Street is built and so far 24,849 m long. 3,46 m more are finished today! How long is the street now?

24,849

+ 3,46

28,309

Main 1: Addition and Subtraction

A cat sits on a branch that is 2,55 m high. Ina is 1,42 m when she puts her arm up she comes 34 cm over her haid. She gets a ladder that is 70 cm tall. Can she help her cat?

Convert:

1,43 m = 143 cm 2,55 m = 255 cm

+ 34 cm

+ 70 cm

247 cm

Main 1: Multiplication and Division

Jenny has a Garden. It is 10 m long and 5 m wide! How big is her Garden?

10 x 5 = 50 m²

Note: If you multiply two length of different directions the result is m².

Main 1: Multiplication and Division

A 1,80 m long wood stick gets cut down into pieces of 45 cm. How much pieces do you get?

Convert: 1,80 cm = 180 cm

180 : 45 = 4

Main 2: Perimeter

• Janina will present this topic with the ‘‘White Boards‘‘

Main 3: Word Problems

• Question 1:

Mr. Greenbird lives in Coconut Grove Island and wants to build a fence around his garden, to protect his purple palm tree from wild animals.But, he wants to install a garden gate that is 127cm wide and plant a hedge with a length of 0.00393km at the property line (Grundstücksgrenze).

How many meters of fence does Mr. Greenbird need if each side of the garden is 4.13m long?

Main 3: Word Problems

• Calculation method.

How many meters of fence does Mr. Greenbird need if each side of the garden is 4.13m long?

Main 3: Word Problems

• Solution 1:

the perimeter of the garden is: 4 x 4.13m = 16.52m.

convert the garden gate in m: 127cm = 1.27m and the hedge in m: 0.00393km = 3.93m

add the fixed elements: 1.27m + 3.93m = 5.2m

subtract the fixed elements from the perimeter: 16.52 – 5.2m = 11.32m

Answer: Mr. Greenbird needs 11.32m of fence.

How many meters of fence does Mr. Greenbird need if each side of the garden is 4.13m long?

Main 3: Word Problems

• Question 2:

Harry wants to build three picture frames. The lengths of these frames should be 180mm each and the width should be 13cm each. In the building supply store (Baumarkt), a ridge (Leiste) has a length of 2.40m. Calculate: 1. How many cm of ridge does he need to build 3 frames?

2. How many cm of the ridge(s) are left?

Main 3: Word Problems

• Calculation method.

1. How many cm of a ridge does he need to build 3 frames?2. How many cm of the ridge(s) are left?

Main 3: Word Problems

• Solution 2:

convert the length of a picture in cm: 180mm = 18cm

the perimeter of a picture is: 2 x 18cm + 2 x 13cm = 62cm

the total perimeter of all pictures is: 62cm x 3 = 186cm

convert the length of the ridge in cm: 2.4m = 240cm

subtract the total perimeter from the length of the ridge: 240cm – 186cm = 54cm

Answer: a) he needs 186cm of ridge and b) 54cm of the ridge are left.

1. How many cm of a ridge does he need to build 3 frames?2. How many cm of the ridge(s) are left?

Main 3: Word Problems

• Question 3:

A square with a perimeter of 0.4 m has been cut in half. Both halfs were put next to each other to form a rectangle (see picture below).

How long is the perimeter of the rectangle in cm?

a) 32cm b) 40cm c) 44cm d) 48cm e) 50cm

Main 3: Word Problems

• Calculation method.

How long is the perimeter of the rectangle in cm?Answer: ? a) 32cm b) 40cm c) 44cm d) 48cm e) 50cm

Main 3: Word Problems

• Solution 3:

convert m in cm: 0.4m = 40cm

the side lenghts of the square is: 40cm : 4 = 10cm the perimeter of the rectangle is made up of 4 complete sites and of 2 half

sites: 4 x 10cm+ 2 x 5cm = 50cm

Answer: e) is correct - the perimeter of the rectangle is 50cm.

How long is the perimeter of the rectangle in cm?Answer: ? a) 32cm b) 40cm c) 44cm d) 48cm e) 50cm

Review: Lessons learned

• Corbi will present the review

• Uli & Corbi will hand out worksheets