You can still access Salesforce Classic modules or you could last time i checked. If a module requires you to be in classic or lightning you can easily switch between them in Set Up. In Lightning click your user potrait and it should be there to switch to classic. If in classic and you need to get to lightning just click on your name in salesforce and it will give you the option to switch to lightning. Is that what you mean?
Some are based on lightning some are based on classic it generally tells you at the top what they based on. So i just switch from classic to lightning following the steps. The new stuff is Lightning but there are plenty of admin beginner modules that are classic. The Admin Beginner Trail is Lightning but for the most of it like creating objects and fields you are only changing the path you follow to get there.
Creating new Objects Lightning 1. Click Cog Icon 2. Type Object in the quick search bar 3. Click Object manager 4. Click new
Classic 1. Click Set Up 2. Type Object in quick search bar 3. Click on objects under create 4. Click new
There are a few difference when going through this like the utility bar for lightning most of the stuff you dont actually touch it.
Half the companies ive worked with or for have been classic and other half lightning so it might seem a little off putting at first but you will quickly be able to replicate mostly for the same things. If you need some pointers on getting through them im happy to help you.
It is kind of frustrating that you can't choose between formats of course - lightning or classic. I realise SF is going down the lightning path so training is to suit, but there is clearly a high enough percentage of SF classic instances being used so training should be there to suit. I understand the basis is the same essentially, but if you are doing Trailhead modules prodominantly in lightning but working in classic, then it is a little confusing...!
Sorry about the long delay in response. There are other sources which are still in classic I think there may even be some free ones alongside paid ones on places like Udemy there was last time I checked. If it is click not code you are mainly doing if you ask around the Admin forums they will probably be able to link you to some official sources other than trailhead. I know they had some workbooks online and PDF's covering a range of things. I found it fairly easy to work out from little snippets of information and reading other peoples questions on these forums. If you can't find what you are looking for if you ask about specifics on these forums ive found people will either give you several suggestions on things you can do or point you to the information.
Creating new Objects
Lightning
1. Click Cog Icon
2. Type Object in the quick search bar
3. Click Object manager
4. Click new
Classic
1. Click Set Up
2. Type Object in quick search bar
3. Click on objects under create
4. Click new
There are a few difference when going through this like the utility bar for lightning most of the stuff you dont actually touch it.
There are some differences with dashboards and graphs but most of the basic admin stuff is really similar.
for instance this is still classic
https://trailhead.salesforce.com/en/modules/admin_intro_accounts_contacts/units/admin_intro_accounts_contacts_basics
Half the companies ive worked with or for have been classic and other half lightning so it might seem a little off putting at first but you will quickly be able to replicate mostly for the same things. If you need some pointers on getting through them im happy to help you.
https://trailhead.salesforce.com/en/modules/platform_dev_basics/units/platform_dev_basics_intro you need to install it follow the modules to go through it.