Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 361 · 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.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) putting the iron away
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) yeast (d) an adult with an iron
4. 4.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) putting the iron away
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a cotton bud (d) a small bowl
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) white paper (d) a battery cell
7. 7.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) lemon juice (d) white paper
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
12. 12.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
13. 13.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
14. 14.⚖️ 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 keep it the same (c) we change it
15. 15.True or false: plugging in the iron is a job a child can do. (a) False (b) True
16. 16.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
17. 17.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
18. 18.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) reading the message
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
20. 20.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) blue (d) green
21. 21.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
22. 22.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
23. 23.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) writing the message (d) cutting the lemon
24. 24.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a mirror (d) a balloon
26. 26.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
27. 27.True or false: ironing the paper is a job a child can do. (a) True (b) False
28. 28.True or false: cutting the lemon is a job for an adult. (a) False (b) True
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) white paper (d) a magnet
30. 30.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
31. 31.True or false: yeast is needed for the secret lemon message. (a) True (b) False
32. 32.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
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 iron setting (b) the same cotton bud (c) the kind of juice (d) how dark the writing is
34. 34.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
35. 35.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
36. 36.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
37. 37.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) cutting the lemon (d) ironing the paper
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) a small bowl
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud

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