Key points:

Build in Blocks

Maths	Maths Operator: Add, Subtract, Multiply, Division Relational Operator:
Logic	Logic value: True, false                   Logical operator: not, and, or
color	Blue, Red, Yellow, Green
Control	Selection: If..then,  if..then..else

Practical 2A: Calculating Body and Mass Index (BMI)

Program requirements:

1.      Input your weight (in kg) and height (in m) in 2 Textbox.

2.     When a Button was clicked. Calculate the BMI ratio with the formula: BMI = weight / (Height x Height)

3.      Show the BMI value in a Label.

Instructions:

A.      Login the web based platform http://appinventor.mit.edu and create a project called BMIcalculation.

B.      Design the layout of your apps in App Designer.

Ø   You have to use at least 2 textboxs, 2 horizontalarrangement, 2 labels and 1 button.

Ø   Rename the ‘Textbox1’ and ‘Textbox2’ as ‘Textboxheight’ and ‘Textboxweight’.

Ø   Rename ‘Button1’ as ‘ButtonCalculate’

Ø   Rename ‘Label1’ and 'Label2' as ‘LabelR1’ and 'LabelR2'

Ø   Change the properties of the component as follows:

                

C.      Build your program with Block Builder. Drag the following blocks and build your program.

Ø   From my blocks 

Ø   From build-in - Maths 

D.     Test your apps with emulator

Ø   Start the emulator and unlock the emulated phone.

Ø   Click ‘connect to device’

E.      Package the phone apps for submission

Ø   Click ‘Package for phone’ and ‘Downloads to this computer’

Ø   Submit the Downloaded file in eclass.

Video 1: Design your Layout

Video 2: Programming using Block Editor

Solution of the apps:

Extension activities

1.          The normal BMI range depends on age. For adult, 18.5 – 25 is normal.

2.          Using the if..then..else control structure, change the label.color or label.text according to the values calculated. You can add a label for this functions.

3.          You can also displayed different image according to the BMI value.