From Longman Dictionary of Contemporary Englishmake a mental notemake a mental noteREMEMBERto make a special effort to remember something Sarah made a mental note to ask Janine about it later. → mental
Examples from the Corpus
make a mental note• I let the subject pass and made a mental note for myself.• I let the remark pass, but made a mental note for myself.• Child circled the classroom, making mental notes of good or negative parenting behavior he would discuss with the adults later.• He made a mental note of the byline above the Globe articles, Frank Dougherty, then sifted through the newspaper photographs.• He made a mental note of the number of coaches and freight cars.• The student should look out for them and make a mental note of their fascinating and beautiful effect.• Just make a mental note of what is around.• As he came in, I made a mental note of where he put the keys.• I said nothing to Liz, but made a mental note to ask her sister about it later.• He made a mental note to buy another chair.• He made a mental note to call her and arrange a time to meet, away from her parents.• She made a mental note to call Marcia when she got home. 