Kodomo no Omocha (TV), 12-sai.: Chicchana Mune no Tokimeki Recommendations
The main heroine in both anime are a bit different in terms of personality and background but both stories are similar in that both girls deal with the problems that come with being a 12 year old girl including love.
Very similar. Both have evergetic girls with twintails, a troublemaking boy, take place in 6th grade, and have a story filled with love and the confusions of growing up. Difference is, Kodocha tends to have a more solid and intricate plot. 12-Sai gives off the impression it was, if not actually, made to give advice to young girls growing up.