Do you use loose parts in your home? They are not a Montessori concept. Montessori materials have a clear purpose and a control of error. Loose parts are simply open-ended toys and are often materials you can find around the home. 

Lots of our loose parts/toys have been inspired by the RIE approach, you can see a list of recommended toys and materials here. If you want to know more about the RIE approach, I have enjoyed listening to and reading Baby Knows Best. We are still using a lot of discovery baskets in our home too. Here are a few of the loose parts and discovery type baskets we are currently using.

1. Stacking Cups
2. Wooden Cars - including the Natural Wooden Car and Hape Red Bus. 
3. Rings - wooden rings, egg rings, metal ring and baby link rings.
4. Sensory Blocks
5. Metal Cups - ours are 2.5 oz condiment cups.
6. Metal Measuring Cups and Measuring Spoons
7. Stacking/Coloured Boxes
8. Playsilks - we have the mini and full size. 
9. Wooden Brushes
10. Wooden Stacking Pebbles
11. Rainbow Geo Blocks
12. Wooden Blocks
13. Balls
14. Nature Items
15. Musical Instruments

The rings, metal cups, play silks, nature items and, instruments are the favorites. My little one is now 10 months old and I feel like this is a really good time (if you haven't already) to introduce blocks. He can stack one block on the other and he loves to knock over his brother's creations. One of the things I like the most about loose parts is that my older kids still love using them, they will still build with blocks or simply build towers with the metal cups - it's a nice way for them to play together.