Here are apps I recommend for students to use as additional resources for learning Chinese.
I generally put the from easy (Row 1) to hard (Row 3). Most of them are only free for a few lessons. If you want to continue, you need to buy more lessons in the app store. You can type the following names to find them. Some of the names are in Chinese.
Row 1: Left to right
1. Learn Mandarin Chinese for Kids Tiny factory
2. Learn Mandarin Chinese for Toddlers Tiny factory
3. First words checklist Chinese
4. Feed me
6. Fun Chinese
7. Chinese Skill
8. Hello Chinese
9. Magikid Pinyin
10. 汉语拼音 （han yu pin yin)
11. 拼音打字练习 (pin yin da zi lian xi)
13. 魔力小孩识字（mo li xiao hai chi zi)
14. Dr. HSK 1