So what the heck does tenten and maru do? Well, recall that Japanese characters usually consist of a consonant and a vowel. If you look at the Hiragana chart from the last lesson, you might notice that those aren't all the consonants. Yes, that's right, there are more: G, Z, D, B, and P. These characters though use the same characters as the K, S, T, and H column, except they include a tenten or maru. It's a little hard to explain, but seeing it this way might make it easier to understand:
K + ゙ (tenten) = G
か (ka) + ゙ (tenten) = が (ga)
S + ゙ (tenten) = Z
さ (sa) + ゙ (tenten) = ざ (za)
And the pattern repeats itself, with: T + tenten = D, and H + tenten = B.
It's different with P though, and this is where maru comes in:
H + ゚ (maru) = P
は(ha) + ゚ (maru) = ぱ (pa)
I enlarged the text to make the maru more visible. On normal sized font, it's so small it may be mistaken for a tenten (ぱ). See what I mean?
Anyways, P is the only consonant that uses maru, so whenever you see a character with a maru, you should know right away that it is a P sound. To recap, H can split into B or P depending on if it uses a tenten (it becomes B) or if it uses a maru (it becomes P).
Now that you know this, you can take a look at the Hiragana chart posted on our last lesson and look at the smaller chart to the left of it. It makes sense now, doesn't it?
Lastly, something to note about these additional characters.
You remember that ち is pronounced chi and not ti, right? And し is pronounced shi, not see? With tenten, these two characters become ぢ and じ, respectively, but they are both pronounced the same: ji. Also similar to this is づ (dzu) and ず (zu), as they are both pronounced zu. It's strange, I know (za, ji, zu, ze, zo for the Z column and da, ji, zu, de, do for the D column). You'll probably see one more common than the other, but that does not mean that they are the same character! For example, you'll rarely see the character ぢ (dji) and づ (dzu) compared to じ (ji) and ず (zu), but they'll appear in some words: つづく (tsuzuku = to continue). つずく (pronounced the same way) is a misspelling for this verb.
And this is the end of our lesson for today! If there are any questions or comments (I know this stuff can be pretty confusing), please post them below!