Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 558 · 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.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
2. 2.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
3. 3.True or false: white paper is needed for the secret lemon message. (a) True (b) False
4. 4.🔮 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
5. 5.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
6. 6.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
7. 7.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
8. 8.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
10. 10.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) cutting the lemon
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
12. 12.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
13. 13.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
14. 14.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
15. 15.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) dipping the cotton bud
16. 16.True or false: reading the message is a job for an adult. (a) True (b) False
17. 17.True or false: cutting the lemon is a job for an adult. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a cotton bud (d) a magnet
20. 20.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
22. 22.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) writing the message
23. 23.True or false: letting the paper dry is a job for an adult. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
25. 25.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
26. 26.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
27. 27.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
28. 28.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) reading the message (d) plugging in the iron
29. 29.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) writing the message
30. 30.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
32. 32.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the same paper
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a cotton bud (d) a small bowl
35. 35.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a magnet (d) a small bowl
37. 37.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a magnet (d) a mirror
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
39. 39.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) yeast (d) a magnet
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True

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