Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 497 · 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.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
2. 2.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
3. 3.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the iron setting (c) the kind of juice (d) the same paper
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
7. 7.⚖️ 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
8. 8.🛟 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
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a balloon (d) a cotton bud
10. 10.True or false: cutting the lemon is a job a child can do. (a) False (b) True
11. 11.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) a small bowl (d) an adult with an iron
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
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 change it (b) we measure it (c) we keep it the same
15. 15.True or false: ironing the paper is a job a child can do. (a) False (b) True
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
17. 17.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
19. 19.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) a cotton bud (d) an adult with an iron
22. 22.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
26. 26.True or false: yeast is needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) a cotton bud
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
30. 30.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
31. 31.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
32. 32.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
33. 33.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
34. 34.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
35. 35.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
36. 36.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
37. 37.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) cutting the lemon
38. 38.🛟 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
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the ironing time (c) how dark the writing is (d) the iron setting
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the ironing time

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