Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 389 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
2. 2.True or false: yeast is needed for the secret lemon message. (a) False (b) True
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a balloon (d) an adult with an iron
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a cotton bud (d) yeast
6. 6.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
7. 7.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
8. 8.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
10. 10.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
11. 11.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
13. 13.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
14. 14.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the iron setting
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) the ironing time (d) how dark the writing is
19. 19.True or false: letting the paper dry is a job a child can do. (a) False (b) True
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) the iron setting (d) the kind of juice
21. 21.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
22. 22.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
23. 23.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) a balloon (d) turmeric powder
25. 25.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a battery cell (c) a cotton bud (d) lemon juice
27. 27.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
28. 28.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) ironing the paper
29. 29.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a magnet (c) lemon juice (d) white paper
32. 32.True or false: putting the iron away is a job a child can do. (a) False (b) True
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
35. 35.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
37. 37.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a magnet (d) turmeric powder
39. 39.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) white paper (d) lemon juice

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids