If you are looking to make the Mother Goose Time curriculum a little more challenging, I suggest adding the more math and literacy workbooks to your daily schedule.
Each book comes chalked full of activities geared for 4-5 year olds. They get to work on counting, matching, rhyming, letter recognition, etc.
Elli has been using these books at home in the evenings when her big sister works on homework. They are great for practicing fine motor skills and gaining more confidence in math and reading.
At the back of each book is a skills assessment area so you can track your child's progress and see if they are where they should be.