Solar System with Astro Cat
By using a character (Astro Cat) to engage with the children user. Uses fruits to describe how different the sizes of the planets are. There are true or false questions which makes this app aiming for the older children age. (unless if I can use a recorded audio to guide the user example: Tap the blue square if Yes and tap the red square if No.)
Calculating your Earth age into Mercury age is quite cool too. if you are 8 years old in Earth but in Mercury you are 36 years old.