Topics 2: Properties and events of a component. Simple calculation and assignment statements.
Key points:
Events and properties of different components
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.
Suggested answer of extension activities