Must download another app to unlock level 8

This is a cute app and my sons were enjoying discovering what each picture was. Then one got to level 8 and in order to play, an ad for a (free) app popped up, saying you had to download it to unlock the next level. The "free" app has in- app purchases in it and as a parent I feel I should know ahead of time that this is being used as an incentive to continue a game. I understand this is a free app but there is already another tab with "More Apps" that takes you to the app store, which is to be expected in a free app... But making a child download an app that has in-app purchases and not telling parents this in the description up front is a bit much... Why not make this a lite version and tell people upfront how many levels can be played, then create a full version for those who want to continue the game... Ill change my rating if the description changes.

specialappssk about CSI for kids