Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 192 · 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 is needed for the secret lemon message? (a) a balloon (b) a magnet (c) lemon juice (d) yeast
2. 2.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
3. 3.⚖️ 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 ironing time (c) the kind of juice
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) lemon juice (d) white paper
6. 6.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
7. 7.⚖️ 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) how dark the writing is (c) the iron setting (d) the ironing time
8. 8.True or false: writing the message is a job for an adult. (a) True (b) False
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
10. 10.True or false: putting the iron away is a job a child can do. (a) False (b) True
11. 11.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
13. 13.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) ironing the paper
14. 14.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
15. 15.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) writing the message (d) plugging in the iron
16. 16.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
17. 17.⚖️ 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
18. 18.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
19. 19.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
20. 20.True or false: ironing the paper is a job for an adult. (a) False (b) True
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
22. 22.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
24. 24.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) a balloon
27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
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 keep it the same (b) we change it (c) we measure it
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a small bowl (d) white paper
31. 31.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) putting the iron away
32. 32.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a mirror (d) an adult with an iron
34. 34.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) turmeric powder (d) a magnet
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) a cotton bud (d) lemon juice
37. 37.⚖️ 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 kind of juice (c) the same paper (d) the same cotton bud
38. 38.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a battery cell (d) a small bowl
39. 39.True or false: letting the paper dry is a job for an adult. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False

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