Price range?
For biology and if you want to get creative, Something like this?
If she likes technology and puzzles- an Arduino Starter kit?
Not an app and not sure if it's exactly what you're looking for but I was showed fold it back in highschool when it first started out. You can manipulate proteins and actually help with scientific papers through wefoldit. https://fold.it/portal/ you have to download it and run it on a computer I believe. Not sure if link will work and sorry if formatting is strange I'm on mobile.
Probably a bit late but since I don't see any other comments, here goes. There's a nice little 3-12volt motor set on Amazon that comes with fans, axels, motors, motor holders, connectors for 9volt batteries and other battery holders, extra wire, and a few more things. Here's the link for that. https://www.amazon.com/dp/B08GPPJR1T/ref=cm_sw_r_apan_glt_fabc_TBPHYD7P88W17ER94TNK?_encoding=UTF8&psc=1
There's also some gears and pulleys sold by the same brand. https://www.amazon.com/dp/B0777L2L7X/ref=cm_sw_r_apan_glt_fabc_JWNNST97XK17FKEACJCJ?_encoding=UTF8&psc=1
I just finished a book on design and tried first to target middle and high school. I decided to concentrate on an easy introduction and get into the main task of explaining design in a way that clarifies all the common terms used around the field. The book is available in paperback and kindle editions exclusively on Amazon at:
https://www.amazon.com/dp/1795855401
The best and most challenging approach is to run a design project that causes people to use technology to prove something works, then build it and SHOW it works. Common problems are eggs dropped from a height without breaking, better mousetrap, etc.
The goals are simple but the execution is hands-on. I'd stay clear of gadget-building (Maker Club) and concentrate on problem solving for a clear requirement. The result is a clearer understanding of the roles of technology, engineering, science and math, without lifting one above the other.
Most STEM curriculum is a mere survey of the various fields but motivating them with a design project would be much better.
There are a ton of great STEM activities for younger kids. Whichever you pick, please mind the screen time involved. Amazon has a lot of great choices for your little girl. My favorite would be Building Blocks You want something that will let her create with her imagination. You don't want her just to follow step by step instructions.
Make up stories with her while she plays. It's a great way to develop her language skills at the same time.
Got it, that would be a lot of books! And of course, I’d be glad to share. Many thanks for your interest, I really appreciate it!
My author page on amazon for my other children’s STEM titles.
This is one of my favorite infant/toddler toys of all time. Have them roll lots of objects (blocks, balls, cars, cubes, food, whatever) down and see which moves fastest. Have them change the angle and try again. Talk about patterns they begin to see. Use it to play telephone or as a telescope. With infants, roll a ball through slowly in front of them to help develop the concept of object permanence. I have 3 kids 3 and under and they all love this thing!