Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 584 · 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? Which of these is what we measure? (a) the same paper (b) the ironing time (c) how dark the writing is (d) the same cotton bud
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
3. 3.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
5. 5.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
6. 6.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
7. 7.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) writing the message
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a magnet (d) an adult with an iron
9. 9.🔮 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
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) a battery cell
12. 12.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
14. 14.True or false: yeast is needed for the secret lemon message. (a) True (b) False
15. 15.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
16. 16.True or false: ironing the paper is a job a child can do. (a) False (b) True
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
18. 18.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a magnet (d) a balloon
19. 19.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) an adult with an iron (d) a cotton bud
21. 21.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
22. 22.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
23. 23.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
25. 25.⚖️ 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) the same paper
26. 26.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
28. 28.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) reading the message
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
30. 30.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
31. 31.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
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: writing the message is a job a child can do. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
35. 35.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) putting the iron away
36. 36.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
37. 37.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
38. 38.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
39. 39.🧺 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
40. 40.True or false: reading the message is a job for an adult. (a) False (b) True

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