Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 597 · 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.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a mirror (d) lemon juice
3. 3.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) ironing the paper
4. 4.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) dipping the cotton bud
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) the ironing time (d) how dark the writing is
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
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.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
10. 10.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) putting the iron away
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) white paper (d) a cotton bud
12. 12.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) blue (d) green
13. 13.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
14. 14.⚖️ 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
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) turmeric powder (d) a balloon
16. 16.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
17. 17.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
18. 18.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
19. 19.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
21. 21.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
22. 22.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
23. 23.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
25. 25.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) writing the message (d) ironing the paper
26. 26.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
27. 27.True or false: plugging in the iron is a job for an adult. (a) False (b) True
28. 28.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) letting the paper dry
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) lemon juice (d) an adult with an iron
30. 30.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ 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 ironing time
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a small bowl (d) a battery cell
34. 34.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a balloon
36. 36.🍋 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
37. 37.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
38. 38.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
39. 39.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same

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