Current　e-learning　systems　are　primarily　resource　oriented,　rather　than　cognition　oriented.　To　reduce　learners＇　cognitive　overload　in　e-learning,　we　proposed　a　novel　e-learning　system　Yotta　tackling　the　problem　of　knowledge　acquisition,　knowledge　presentation,　and　knowledge　resources　management.　The　granularity　for　knowledge　acquisition　in　Yotta　is　based　on　knowledge　units　that　are　the　smallest　integral　learning　objects　in　a　specific　domain.　Knowledge　presentation　and　navigation　in　Yotta　is　based　on　knowledge　maps,　which　can　exhibit　knowledge　and　the　intrinsic　knowledge　relations　at　both　concept　level　and　knowledge　unit　level.　Automatic　knowledge　unit　extraction　and　knowledge　map　construction　techniques　are　also　discussed　in　this　paper.　Yotta　allows　for　huge　concurrent　access　and　enormous　resource　storage,　as　it　is　deployed　on　a　cloud　platform　with　the　Hadoop　distributed　file　system.　The　Yotta　demo　has　already　been　implemented　on　our　campus　network,　and　has　been　approved　by　hundreds　of　students.　Yotta　offers　new　ideas　for　building　elearning　systems,　and　its　core　techniques　still　require　further　study.　©　2010　IEEE.