Go into the Grown Ups area of the DoodleMaths or DoodleEnglish app and enter your password.
Then select Settings. Once in, scroll down the list and tap on Reminder Notifications.
To set a schedule move the DoodleStar icon across the bar, this will indicate the time you would like to remind your child to start Doodling! If the bar appears grey, tap the switch on the left hand side of the bar to turn it on (it will go from grey to green). This will allow you to move the slider across.
If you want to set reminders for each app, you will need to go into each app individually to set this.