In masculine singular nominative, "ten" = this and "tamten" = that (so tego/tamtego in Accusative*). However, at least to my personal 'feel', Polish doesn't care that much about the distinction between this and that, unless you need to show the contrast between ten chłopiec and tamten chłopiec (because you talk about both of them at once). So it's quite probable that the course will accept 'ten' for both 'this' and 'that'.
You could try having a look here.
*Some masculine nouns belong to a, let's say, sub-type which has the Accusative form identical as in Nominative, so the pronoun behaves respectively. Normally you have "Znam tego psa", but then you have "Znam ten autobus". But better just focus on the more usual things now ;)