The idea of curriculums and themes and adult led teaching vice child led learning were things we discussed in our childcare association at one time when setting up the workshops for the new year. A lot of the terms out there are confusing Early childhood for example means toddler to me but if you look at any teaching resource manual from the major publishers that says themes for early childhood on it the age range of the intended student is age 3-5 years. For us in Ontario at least that is the JK/SK group not what we have in home daycare for the most part. What this does is confuse both caregivers and parents on exactly what they are supposed to be "doing" with children aged 1-3 years. This group needs to experiment with why towers fall over when you put the big block on the top and the small one on the bottom or why only 6 hot wheels cars fit in the blue tin but 11 cars fit in the red tin which is bigger. That is the curriculum of toddlers. And it can be planned just the same. Gather the children together with some objects (whatever they are interested in at the time - cars, dinosaurs, lego) and some containers and count as you put things in and out of them together. Then leave the containers and objects available for the children to redo the experiment. This is math and science at the toddler level.

About the letter of the week concept - there is a website I think it is just called letteroftheweek.com that does just that. As someone mentioned these are just parents that are sharing what they are using with their own children. In many cases they are homeschooling families. I have never bought these types of programs since I am not a sit down do seatwork kind of teacher - here we "learn to play and play to learn".