Toddlers are so full on and demanding and 100% every second of the day precicely so that you do give them all your attention.
If she sat sweetly playing with her blocks I would get on with my day (by which I mean Mumsnet).
Instead every minute is "Take that out of your mouth, oh careful that's heavy, shall I help you with that? No you'll fall, hold my hand. Gently with the kitty, oh very good aren't you gentle, no, NO GENTLE like you showed me before, no the kitty doesn't eat crayons, you spit it out too, all of it, hang on I'll get a cloth. How did you get up there? Okay I've got you. Alright but go backwards and feet first. Where's your book? Shall we sit down and look at your book for a minute? What have you got in your mouth now?"
And so because she is forever in some sort of peril from swallowing screws, falling off the table, upsetting the cat, I have no choice but to interact with her the whole time she's awake and so every minute of her day is interactive and a learning process.
It has taken me three children to work this fairly obvious thing out.