Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 331 · 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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
2. 2.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
4. 4.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a battery cell (d) a balloon
6. 6.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) putting the iron away
7. 7.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
8. 8.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
10. 10.⚖️ 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
11. 11.True or false: letting the paper dry is a job for an adult. (a) False (b) True
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the iron setting
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
14. 14.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) reading the message (d) cutting the lemon
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
16. 16.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) putting the iron away
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) turmeric powder (d) an adult with an iron
18. 18.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
19. 19.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) dipping the cotton bud
20. 20.True or false: putting the iron away is a job a child can do. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
22. 22.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
23. 23.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) lemon juice (d) a cotton bud
25. 25.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
26. 26.True or false: cutting the lemon is a job a child can do. (a) True (b) False
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) a mirror (d) white paper
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) turmeric powder (d) a balloon
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
30. 30.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a balloon
32. 32.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
33. 33.True or false: letting the paper dry is a job a child can do. (a) True (b) False
34. 34.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
35. 35.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
36. 36.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) putting the iron away
37. 37.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
38. 38.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ 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 measure it (c) we change it
40. 40.True or false: writing the message is a job a child can do. (a) False (b) True

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