"The children eat rice."
Translation:De kinderen eten rijst.
Go to the tips & notes section of basics 1 and it gives a rundown of the differences between de and het for the singular noun.
However, in this case, the golden rule to remember is that de is always used for plural nouns. De man (the man) = de mannen (the men), het meisje (the girl) = de meisjes (the girls).
Hope it helps!
Every noun in Dutch have one of three genders: masculine and feminine (together they are called common, as they are treated the same way and make up about 75% of nouns in Dutch) or neuter. The gender has effect on many things-the 'the' word, for example. Common (feminine and masculine) nouns get "De" as in "De krant" meaning 'the newspaper', and neuter get "Het" as in "Het meisje" meaning 'the girls'. There are a few rules that can help you understand when a noun is common and when it is neuter, however in many cases there is no rule, and you just have to learn and remember what gender each noun is. There are also more rules about when to use "De" and when "Het"- for example pluralized words always use "De" (as in "De meisjes". You can find more information about "De vs. Het" and nouns gender in tips and notes, under "De and Het" section I think. And sorry for writing so long, got carried away:)